Category Archives: freediving gear

The surprising truth about your wetsuit, and staying warm while freediving

Staying warm while freediving is an art, especially in colder waters. During a normal 2-hour dive session you can easily lose more than 700 kcal just on heat loss, and if you lose heat too fast, your dive session will be cut short. Here I’ll share some surprising information about the performance of your wetsuit, and what you can do to stay warm in the water.

High heat loss despite a wetsuit

Conductive heat loss is something we can calculate. I am not going to try to bore you too much with the details, so here is the condensed story.

How much heat you lose through conductive heat transfer depends on four things. 1) The temperature difference of your skin and the water around you, 2) the thermal conductivity of your wetsuit, 3) the thickness of your wetsuit, and 4) the surface area of your body.

Wetsuits contain up to 94% nitrogen bubbles. The nitrogen is what prevents heat loss. The neoprene itself is actually quite conductive. Nitrogen compresses just like air, so at depth the suit becomes thinner and the overall heat conductivity increases.

Conductive heat transfer does not include water sloshing through your wetsuit. It is simply the amount of heat you lose if you were to be still, in still water.

Here are some interesting results based on conductive heat transfer alone:

  • A diver in a 3 mm suit and 25ºC (77ºF) water loses more heat than a diver in an 8 mm suit in  8ºC (46ºF) water
  • Heat loss at 20m is 4 – 5 times as high as at the surface
  • Heat loss at 40m is 7 – 8 times as high as at the surface
  • You will commonly lose at least 500 kcal of energy during a 2 hour dive session
  • At 40m depth, you can lose as much heat as a medium sized space heater generates (3000W),  depending on the thickness of your wetsuit
Surprise! You lose more heat through conduction in tropical waters in a 3 mm suit than in frigid water in an 8 mm suit.

Planning your dives so you stay warm

When I initially calculated the difference in heat loss between cold and warm water divers, I thought I made a mistake. How on earth can a diver in 25ºC water with a 3 mm lose as much heat as a diver in 8ºC water with an 8 mm suit? I know from experience that I can spend all day in warm water, and only a couple of hours in cold water.


The answer is that conductive heat transfer is not the full story. If the sun is directly above you (midday on the equator), it will supply the earth surface with >1000 W/m2 of heat. Those 25ºC waters we talked about earlier get much more direct sunlight. In a 3mm suit you only lose ~300 W at the surface,  so the sun is instrumental in keeping you warm.

The sunlight hits regions farther from the equator such as Canada and New Zealand at an angle (see also: solar irradiance). Because of that, the sun supplies much less heat to the freedivers that call these waters home. In these regions, if you want to stay warm you need to plan your dives when the sun is high. That is not difficult in the summer, but in spring and fall you should try to dive in the afternoon, preferably on days without cloud cover. In the winter… may Poseidon be with you.

Wind and evaporation

Part of your body is above the surface during your breathe up. If the apparent air temperature (apparent air temperature takes into account wind chill) is lower than the water temperature, this will cause you to lose heat faster. The increase in heat loss can be as much as 10%, if you dive during a 0ºC day.

More important is the effect of evaporation. When you are above the surface, the water on your suit will evaporate. During evaporation, liquid water extracts heat from its surroundings. Unfortunately its surroundings are you, or rather, your suit.  Evaporating water costs a lot of energy, and how cold you become during a dive might be directly proportional to the rate of evaporation. Wind will increase the rate of evaporation, and so does heat. If you have a smooth skin suit, there will be less water to evaporate than if you have a lined suit.

Diving style and getting in and out of your wetsuit

Diving style is another big part of staying warm. Our muscles are very inefficient, and about 80% of the energy we use is lost as heat. A more active diving style will keep you warm for longer. You will of course sacrifice some performance.

Lastly, what you do before you get in the water will also affect how warm you will be. Make sure to store your wetsuit in a warm(ish) place before a dive session, and try to stay warm while you change. I know one diver that changes in a bathing robe, and transports his wetsuit in a cooler with jugs of hot water. The jugs of hot water do excellent service as a post-dive shower.

In conclusion:

  • Try to dive when the sun is high if you are far from the equator
  • Try to dive in low winds
  • Check the weather forecast and wear a (thicker) suit if there is cloud cover
  • Adjust your diving style to suit the water temperature. Long line diving sessions, deep targets and hangs are for the summertime
  • Stay horizontal at the surface, to allow your entire body to be heated by the sun (if there is some)
  • Try to stay as warm as you can before you get into the water
  • Diving with a smooth skin suit is warmer than diving with a lined suit of the same thickness


Are all fins created equal?

This post was submitted by Dave Forcucci, a freediver based in Washington State. Dave decided to buy an underwater speedometer and to test freedive fin efficiency. You can read the results of his extensive testing here.

It is difficult to imagine where we would be without the information available from the Internet.  Back in the day when we relied on local dive shops for equipment the availability of freedive gear was very limited.  Fortunately we still ventured underwater.  Now with access to a world of freediving resources, we are able to fine-tune our gear and techniques.  Of course before diving in, a freedive course is essential for safe and informed breath hold diving.

With our freediver course under our belt we are familiar with the different pieces of equipment, which thankfully are not many. This is why we like free diving to begin with.   Now we are ready to go diving.  Well maybe.  You are deciding which mask fits best on your face, which snorkel feels best in your mouth and what flavor fins appeal to you and your budget.  You can ask your dive buddies and your free dive instructor about which they prefer and you will, most likely, get a range of advice.  But equipment is personal and we all choose what we believe will work for us, and like most things in life we make compromises.

freedive fin efficiency
Ready for some rigorous testing

What you should know about freedive fins

In this piece we are only going to consider fins.  And there are lots of choices out there.  But basically you choose either a plastic blade or a composite blade that could be either fiberglass, carbon, or a mixture.  Having a list of requirements is always a good thing before you go cyber shopping.   These requirements are personal choices so I will use myself as an example with the understanding that yours may be very different.  The requirements can be listed in order of priority, depending on who is doing the fin shopping.

A comfortable foot pocket is important and in a perfect world you could try on each brand and go for a swim. In reality we have to guess and hope it fits well.  Next requirement: Blade angle.  I learned from experience that it is easier to swim on the surface with a 20 degree angle or so between the blade and foot pockets.  These days most bi-fin blades are manufactured with an angle but some are not.  Likewise, monofins commonly have an angle between the foot pocket and blade, which is helpful for swmming and gliding.  Unlike bi-fins, monofins typically do not have a bent blade, instead the foot pocket is modified to a 20 degree angle. One monofin manufacturer sells a monofin with a bent blade.  This reduces the weight on your shoulder as you tote your fin to oceans and pools from 4 kg (9lbs) for a monofin with angled foot pockets to less than 2 kg (4.5 lbs) for a monifin with an angled blade.  Which is more efficient in the water is yet to be determined.  Other fin properties you need to think about before you buy are the stiffness: soft, medium and hard.  And then of course there is durability, which is dependent on the type of material that the fin is made of. Last but not least: budget.

Measuring freedive fin efficiency

As we shell out hundreds and hundreds of dollars for fins we wonder whether this or that feature will really make a difference?  Or maybe we just hope that paying more will get us more efficiency in the water.   Fin performance is mostly subjective but I was pondering whether there is a way to empirically compare fin performance.  Back on our beloved Internet I found a study on SCUBA fins that compared over a dozen fins using multiple measurements.  It was way too involved for what I wanted to do but it gave me some ideas.  The author of that study mentioned an underwater speedometer that sparked my curiosity.  After another session on the Internet I had found an electronic and a mechanical underwater speedometer.  I was amazed these were available and a guy living across the state from me made the mechanical one.    The cost was reasonable and this gem would allow me do some empirical testing.  The electronic version was out of stock with no demand for manufacturing more.  It turned out the diver from Spokane had been testing SCUBA fins himself for over 20 years and his conclusion was that the bottom line on efficiency was max speed.

An underwater speedometer
An underwater speedometer

Others may suggest that kick cycles and other factors are important too, and they may be, but max speed would provide a standardized measure to compare fins.  I videoed the speedometer gauge with a Gopro to make sure I had recorded the speed correctly.  I could mention the various brands and flavors of fins I tested but the main characteristics are listed instead.


Fin type Blade/stiffness Blade material cost (US$) Speed (MPH)
Scuba/military Short blade Rubber 50 2.7
Freedive bi-fin Two brands Plastic 100 2.9 – 3.0
Freedive bi-fin Medium Fiberglass 300 3.3
Freedive bi-fin Soft Fiberglass 150 3.3
Freedive bi-fin Soft Fiber/Carbon 250 3.3
Freedive bi-fin Soft Carbon 500 3.3
Freedive bi-fin Medium Carbon 500 3.3
Freedive monofin model A Medium Fiberglass 200 3.4
Freedive monofin Model A Soft Fiberglass 200 3.4

The main points of the results are that going from Plastic to composite gets you a 10% increase in efficiency.  I can tell you from experience you might need that efficiency some day if you need to swim against our testy currents to get back to the boat.  But surprisingly, whether the fin was fiberglass or carbon, soft or medium stiffness they all had the same efficiency.  The monofin was a little faster but not as much as I expected. However, I felt like I could have used more room than a pool affords to really work the monofin to potential.

freedive fin efficiency
Dave holding the speedometer

Based on these non-scientific but empirical results, I don’t need to spend the extra cash for carbon which is good for my budget and the robust fiberglass construction will handle about anything I or the sea could throw at it.  As far as blade stiffness goes, I can choose either since they had the same max speed but I liked the soft blades. Soft blades have a wider range of resistance.  Kicking normally at slow speeds was effortless compared to the medium bifins, which required more effort to get the fins moving. Of course this is important, since we need to conserve oxygen.

This was a fun experiment and I hope it helps you while you contemplate your next freedive fin.  In our high-tech world we can get lost in the details. However most of the improvements in design may never be realized as we fin out to the next line dive or kelp bed.  But if we believe a particular fin will give us an edge, even if only a psychological effect, that could translate to better performance and possibly survival.  Just remember to peel off the soft #1 sticker.





Holistic Freediving by Eric Fattah

About Eric

If you have not heard of Eric Fattah but are interested in the history of competitive freediving, now is the time. In 1998 Eric invented fluid goggles, not realizing that Roland Specker had invented similar goggles in France but never marketed them. In 2001 Eric set the first world record with a monofin in constant weight (- 82 m). He dove to -80.5 m in Vancouver without a wetsuit in waters that are approximately 5 °C (41 Fahrenheit) below the thermocline. Eric dove FRC (Functional Residual Volume: diving on an exhale) for four full years, in an attempt to counter decompression sickness and registers his deepest FRC dive at Vertical Blue to 71.9 m. His experience with decompression sickness led him to implement the first experimental decompression sickness algorithm for freediving in his Liquivision dive computers.

Eric is a world class diver who has invented many techniques, and coached well known freedivers such as Branko Petrovic and William Trubridge. He wrote ‘Holistic Freediving’ in 2012, a book designed for freedivers who want to do targeted exercise to increase their CO2 tolerance, low O2 tolerance, diving reflex, and have specialized (cross-)training programs. The book is phenomenal and contains so many novel approaches to freediving that it is well worth the price tag (US$ 95).

Holistic Freediving by Eric Fattah
Eric Fattah

Holistic Freediving

One part of Eric’s phasic training that you will learn about in Holistic Freediving is ‘foundational training’. This training allows you to become better able to withstand hypercapnia and hypoxia. Even better, it will do so without pushing you to the limit and requiring many days of recovery. Forget max attempts until you have laid the foundation. You will be better able to cope with the deep dives, without having lost many training days because you needed to recover. The cross-trainings described in this book are also novel and very effective. No more Wonka tables or simple static tables. Some of Eric’s dry static tables are done with the help of pure O2 and an oximeter. Other tables incorporate exhale statics and hyperventilation. They are intense, but extremely effective. Within three weeks of doing one cycle of static trainings weekly I managed to do a 3 min 45 breathhold on an exhale. My personal best before that? One minute forty seconds.

The price of the product [95 USD] is proportional to the lifetime of secrets it contains and the extraordinary tribulations I went through to discover them – Eric Fattah

Holistic Freediving by Eric Fattah sample

Mouthfill equalization by Eric Fattah

Ask Eric for a copy below:







Repairing a fiberglass monofin: lessons learned

This post was submitted by Luca Malaguti, a freediver based in Vancouver, Canada.

A few months ago I was diving with my fiberglass monofin, looking for crabs near the shore. My fin got stuck between two rocks in a narrow passage.  To my dismay, a little bit of torque was enough to create a 10cm fracture in my monofin (see the picture below). Not only was my monofin fractured, but the location of the crack was so  unfortunate that with each undulation of the fin the fracture would inevitably propagate further.

repairing fiberglass monofin
See here the crack in my fiberglass monofin. The area around it is already sanded

My fiberglass monofin:

Here’s a little history about my monofin. I purchased it from, and had it (expensively) shipped to Vancouver, BC after having to pay even more in import fees. I bought the ‘Sport’ fin from the brand Leaderfins. Once it arrived, I noticed that both foot pockets were labeled “left”. On top of that the monofin was not symmetrical: one half was longer than the other by a few centimeters. As a starting fin it does the job, but beware of purchasing the cheapest products on the market. This fin was obviously improperly manufactured (the fracture itself was unrelated to its manufacturing).

Equipment for the repair job:

Fibertek, a fiberglass dealer in Vancouver, BC ( specializes in all fiberglass types and glues. I bought the toughest, and most heavily woven type of fiberglass (their medium weight cloth yard), and a special type of epoxy glue (the 250 mL epoxy resin for wet & cold curing and 125mL epoxy hardener both from Fiber Craft Aqua-Set). I used them according to the instructions (a 2:1 ratio) while keeping in mind temperature and humidity effects on setting time. In order to  repair a monofin, you will also need a stirring cup, a measuring cup, stirring sticks and a variety of sand paper (I suggest 80, 200 and 400 grit). You should also have nylon gloves and a mask, a wooden table board and a sharp knife (or better yet an X-Acto knife or even a scalpel to cut the fiberglass).

fiberglass monofin
Supplies for the repair job

The fix:

I sanded the spot around the fracture using the 80 grit sand paper around the crack. I then cut the fiberglass cloth with scissors but quickly learned this is a bad idea! Use a sharp knife instead on a flat wood surface to get nice clean edges, otherwise you’ll destroy the woven sheets and make a mess everywhere!

After cutting the fiberglass into strips (starting at 3cm x 5cm), I laid them perpendicular to the fracture and saturated them with the mixed epoxy. They have to be soaked but beware of putting on too much epoxy!

Subsequently I layered the fiberglass on top of each other over the damaged zone and allowed the epoxy to cure (2 – 3 days in a dry area).  Once everything is dry, you can use the 200 and then 400 grit sandpaper to smoothen the fiberglass. If you wish to paint it, make sure you use a paint specifically for epoxy and intended for marine activities.

Hard Lesson Learned:

Here’s the important part and what I learnt from my mistakes.

Patience is a virtue when repairing monofins. I should have been much more patient with fixing it: setting only a few layers at a time, allowing them to dry, testing the rigidity and then continuing with one layer at the time. The rigidity of a monofin can make or break your dive.

Secondly, pressure! I never thought of the epoxy as a chemical reaction but or course it is, and so if the layers aren’t tightly packed there will be some gas/air bubbles forming in between them. This will cause the fiberglass to crack or separate once force is applied. You really shouldn’t underestimate the amount of force generated while kicking underwater! I found this video, obviously after I made the mistakes, ( showing a method in drying the fiberglass epoxy using a “non-stick” polyethylene plastic, foam pads and weights.

To sum up the last two paragraphs: you should add layer by layer patiently. Allow them to dry, in the right environment, each time under heavy pressure. Failing to do so will result in improper settling of the fiberglass layers.

On the right hand side of the fin, the fiberglass/epoxy adhered properly to the fin’s natural fiberglass (picture below). On the other side it, the force of undulating the monofin was strong enough to rip the edge’s off, and then with water intrusion it just detached all the layers. Properly sanding down the surface before can go a long way; it will help the epoxy adhere to the smooth surface (which I forgot to do on the left side).

To be continued…



Taking care of your freediving wetsuit

The first wetsuit I ever used for freediving was a surfing wetsuit. The finest cheapest I could find. It came from Decathlon in France, and had a 5.5/4.5 mm longjohn and a 5.5/4.5 mm jacket. Combined I had 11 mm of neoprene on the core, and 4.5 mm of neoprene on my limbs. That wetsuit lasted forever. It was also about as flexible as a wooden board, and very heavy.

Diving in Vancouver in Winter, the water was probably 8 degrees C or less. This is me in my surf wetsuit, with scuba fins. Photo by Todd Kabaluk
Diving in Vancouver in Winter, the water was probably 8 degrees C or less. This is me in my surf wetsuit, with scuba fins. Photo by Todd Kabaluk

My next wetsuit was an actual freediving wetsuit, a 3mm speardiver from the freedive store. I still have it, although the original 3 mm neoprene now is about 1.5 – 2 mm thick. The wet suit has an unlined inside, commonly referred to as ‘open cell’, meaning that there is no lining on the rubber. Rubber against skin. That whole story of having a thin layer of water to help you stay warm? Total nonsense. If you have less water and/or water flow in your suit you are going to stay much warmer. Compared to my surf suit, diving felt like a trip to heaven and back. I then got a suit from Oceanos in Greece. Not the best suit I ever bought. It was a cheap custom suit, but the fit was not perfect. After a year of diving, the original 5 mm has compressed to about 3 mm.

I now dive with a suit from Azure Passion (review here). It is 8 mm thick, and so far (after 6 months of diving) it is still 8 mm. I take a lot more care with this suit, because it feels like a second skin, and, I really should stop buying a new suit every 8-12 months.

freediving wetsuit
Getting ready to dip into 12 degrees C water with an unlined wetsuit. Photo by Rick Waines

Simple tricks to make your freediving wetsuit last

  • Make sure the neoprene does not compress

Store your suit on a shelf without folds (My pants are folded once, and of my top the sleeves are folded at the shoulders). Do not put anything on your suit. I repeat. Do not put anything on your suit. Not your divelight, not your mask, and not your diving weights. Especially not your diving weights. If neoprene compresses it will lose its insulation. Not a big deal if you dive with a 1.5 mm in the tropics, big deal if you dive in BC in water that can be below 5 °C.

I stuffed my first suits into the smallest bag I could stuff them into. It was handy, especially when I lived in my van for 8 months. But it definitely was not good for the neoprene. Now I use a huge bag for my suits so that they have plenty of space. The quality of the neoprene is another factor. Yamomoto and Heiwa neoprene are currently the best available to my knowledge.

  • Make sure the neoprene does not stretch

You can keep a wetsuit on a hanger but some neoprenes tend to stretch if you do this.. This doesn’t happen instantly but it sure does happen. If it does you have created space for water to slosh around and this will keep you cold. This is part of the reason I keep mine lying on a shelf.

  • Take care of the small nicks and cuts as soon as you can

If you have an unlined wetsuit, don’t breathe at it! Chances are you’ll create a hole. These suits are fragile. Even a fingernail can create a small cut. That small cut will turn into a tear very soon. Keep neoprene cement in your diving bag (put 2 ziplocks around it in case it leaks) so that you can mend your suit on the go. Make sure you can put your suit on and off without having your fingertips against the rubber.



Manage Your Mind by Sara Campbell

Manage Your Mind is part two of the Yoga For Freediving series by Sara Campbell. Manage Your Mind is a series of lectures and guided meditations that are designed to help you quiet your inner demons. Both the demons that tell you to go too deep too fast, and the ones that tell you to come up early.

manage your mind
Sara Campbell running freediving courses in
Dahab. Egypt. (Photo credit: Dan Burton)

Sara teaches us this with the help of Kundalini Yoga meditations, that are meant to balance your ‘positive mind’, your ‘negative mind’ and your ‘neutral mind’. Additionally one pranayama is designed to stress your body through breathhold, which both triggers your fears so you can confront them, and helps you develop the strength you need to overcome them. The awareness of your own mind and how it behaves during stress (long, deep dives, or just breath holds in general) is key if you want to improve in freediving.

Interested? Check the Yoga For Freediving website.

As with part one of the Yoga For Freediving series, Deep Relaxation, Manage Your Mind is for the freediver who is held back by the mental aspects of freediving. Even if you believe more physical training is what you need to overcome squeezes and blackout , the chances are that balancing your physical and technique training, with getting to grips with your thought patterns and how they sabotage you, is what is really going to set you straight for the longterm. Meditating in general will have positive effects on all aspects of your life, not just your freediving. Sara Campbell’s course is unique in that the lectures combined with the mediations covered in Manage Your Mind create a course that is especially geared towards freediving and very useful for those freedivers that feel the mind needs more direction during long dives and breath holds.

What you get:

  • About two hours of video lectures and meditations
  • 22 How-to videos covering the essential basics of Yoga For Freediving

Manage your mind by sara Campbell

Personal Experience

I meditate daily, and have done so for a long time. Hence, my routine was established before I did this review and so I have not followed Sara’s recommendations to the letter. However, the course did make me reflect on what mind dominates during my dives (positive, negative, neutral) and that awareness has helped me in my dives. It has not produced a measurable difference in length or depth (yet?), but my peace of mind during dives is greater, because I have a better handle on what exactly makes me stay down, or come back up to the surface.

Yoga for Freediving: Part 1


Yoga for Freediving by Sara Campbell

Yoga for Freediving is one of the best ways to train for freediving. Pranayama, meaning breath control in Sanskrit, is a discipline that finds its origin in ancient India. In western culture, yoga is commonly seen as a stretching exercise, but it is much more than that. Yoga increases the awareness of the body and the control of both breath and mind in ways that a stretching exercise can never do on its own. You could argue that freediving is actually a form of yoga.

yoga for freediving
Yoga for Freediving: deep relaxation will be launched on June 21st 2016; International Yoga Day

Sara Campbell is a four times world record holder, with a personal best CWT of 104m. It is the practice of yoga, and the mental and physical benefits of yoga that have allowed her to get there. Sara is releasing her first yoga for Freediving course on the 21st of June, International Yoga Day, and Freedive Wire has had a chance to review it.

 “Freediving, and yoga and meditation are more than inextricably linked, they are one and the same thing. If freedivers want to create the best foundations for their training, and really see their performance improve exponentially, meditation and disciplining the mind is the one place they need to focus their attention.” – Sara

Yoga for Freediving: Deep Relaxation

Deep Relaxation is the first of six of the Yoga for Freediving courses. It is a resource that is beneficial for divers of any level. Deep Relaxation is an online course that works mainly with simple meditations, exercises and lectures. By signing up you are effectively inviting Sara Campbell as your private yoga teacher to guide you through meditations and yoga postures. Within the course you can find 28 lectures that add up to about 6 hours of material (22 of these are core How To materials which appear in every course to ensure you have the basics to hand each time; the unique content to every course is around 2 hours per course).

The most important videos, the guided meditations and lectures, are also downloadable as mp3’s. This is a great addition, because you can download them to your mp3 player and do them in the park if you wish. Nothing like meditating on the beach, just before you get into the water.

The videos are highly geared towards freediving, and all contain Sara’s personal perspective on how it affects performance. An example of a ‘how to’ video is ‘how to get the deepest inhale’. It won’t get much more applicable to freediving than this.

“There is more than enough information available for freedivers on the technical aspects of the sport, i.e. how to dive. But to date there is really no structured approach tailored to freedivers explaining the essentials of spirituality within freediving or teaching how to integrate yoga and meditation into their training. Learning to master the mental and emotional aspects of a dive are the make or break of every experience in the water. I’m excited to finally address this crucial aspect for freedivers of all levels.” -Sara

yoga for freediving
Sara teaching Kundalini Yoga. Photo credit: Embah Safari

Personal experience

When I started freediving, I did daily yoga sessions and often meditated outside of that. These yoga sessions were not geared specifically to freediving, but they had a profound effect on my performance. If I meditated before statics, I would get contractions after 3 ½ minutes (my p.b. then was 4 minutes). If I do not meditate at all, my contractions start at 2 – 2 ½ minutes (my p.b. now: 5:20 minutes.

My most relaxed diving session of this season, was after I had started reviewing yoga for Freediving, and specifically, did a 40 minutes guided meditation by Sara. I believe Yoga for Freediving is a great resource for all freedivers that you can keep referring back to and I think many freedivers will agree with me.

Find out more here.










Why freedivers love or hate the Aqualung Sphera

The Aqualung Sphera is one of the most celebrated freediving masks currently available. It is has an unparalleled field of view, and that is combined with a very low internal volume. However, there are also cons to the Aqualung Sphera freediving mask, such as the plastic lens and the distortion because of its curvature. Opinions are strongly divided, so read on to find out whether the Aqualung Sphera is for you.

Aqualung Sphera: low internal volume

The Aqualung Sphera has one of the lowest internal volumes of any freediving mask. This coupled with a high compressibility ratio means that you will not need to equalize it until well past 25 meters. According to some divers the first time they equalize the mask is past 40 meters. Most other masks need to be equalized before reaching 15 meters. This also means that you will have more air left to equalize your ears and sinuses when diving with an Aqualung Sphera, as compared to other masks.

The exact volume depends on the shape of your face, but is probably around 65 ml with a loose fit, compared to an average 120 ml for other freediving masks.

Aqualung Sphera: large field of view

Because its plastic lenses are curved, you get a 180° field of view with the Aqualung Sphera. This is unparalleled, because any other freediving mask has either straight lenses, or lenses at a slight angle. The field of view is one of the selling points of the Aqualung Sphera.

Aqualung Sphera: mediocre lens quality

Before you get an Aqualung Sphera, because it is supposedly the best mask on earth and you will get that coveted panoramic view, there are caveats. The plastic lens is inferior to tempered glass lenses in the quality of vision. Think of it as the difference between HD and 480p. There is a significant drop in quality of vision.

Aqualung Sphera: distortion

The curved lenses also cause distortion that increases towards the periphery of your vision. This is something that you will have to get used to, and some divers never actually do get used to it. The first time I dove with an Aqualung Sphera I was disoriented to the point of nausea and had to support myself with my hands when I was coming out of the water. This was almost gone after the first four dive sessions.

Aqualung Sphera: longevity

Because of the soft silicone skirt and the plastic lenses, Aqualung Sphera masks do not last very long. One of my friends loves the mask but he says he buys them in threes now. On average they last a year (edit 8-aug-13: one of my friends tells me hers lasted for an average of 3 years). The lens is more prone to pop out because there is no rigid frame to the Aqualung Shera and it is prone to being scratched. One sand grain on your finger or glove when you are cleaning the mask and the lens might get scratched. However, it comes in a plastic box and if you take care of it, it should last you a long time. Make sure to use two hands when putting it on and off.

aqualung sphera
always use the provided case for transport. This is not a rugged mask.

Personal experience

I have given the Aqualung Sphera my best try but I can’t use it for a few reasons that are very personal.

1) The fit on my face is not great. I have a nose that is slightly too big for the nose pocket of the Sphera and it ends up creating suction and pulling my soft palate up. Result is that I am unable to equalize past ~25 meters.

2) I never got over the distortion and quality of view. Most of my dives are in order to enjoy looking around at depth, not to get as deep as I can. Even when I am line diving, I dive like I would when I am sightseeing because that is what I am training for. So for me, a mask that provides me with more clarity of view is simply better. Maybe I would have not been bothered so much by it if I could equalize deeper though.


The freedivers I know either love, or hate the Aqualung Sphera freediving mask because of the reasons above. If you can get over the distortion and quality of view, the Sphera is probably a great mask for you.

the Sphera on



Azure Passion custom wetsuit review

Azure Passion is a company located in sunny Greece that makes wetsuits, spearguns and fins and ship all over the world. This is a review of an 8 mm custon smooth/cell wetsuit. The Azure Passion custom wetsuit is a very good suit with attention to detail that is not painful on the wallet.

Azure Passion custom fit

The fit of the azure passion custom wetsuit is perfect. The sizing chart of the wetsuit has over 25 entries, so you will be measuring for a while, but the result is great. The perfect fit will assure that you are kept cozy warm and will keep water from sloshing through your wetsuit. The legs and arms are sized according to the thickness of your upper and lower arms and legs, and the circumference of your knees and elbows. This means that the suits limbs stay where they are supposed to and you will keep the sleeves to where they need to be: one centimeter past your wrist and ankle. This is not trivial with a wetsuit designed for cold water, because you need to make sure that you do not get cold water sloshing into your neoprene socks and gloves. (Note: I recommend you go to a tailor with the measurement sheet and a photo of a wetsuit so that you can get your sizes taken professionally. An excellent fit starts with excellent measurements).

Azure Passion Wetsuit Material and insulation

Azure Passion custom wetsuits are made out of quality Heiwa AWS (accompany with skin) neoprene, which is elastic, tear resistant, and keeps its elasticity for a long time. This particular smooth/cell (smoothskin on the outside, open cell on the inside) has no fabric lining the outside or inside. I was surprised at the elasticity of the material, even though 8 mm is a lot of neoprene.

I am a wimp in cold water. My apnea ability goes down and frankly, I don’t like being cold. There are some divers here along the Pacific Northwest that dive in a 5 mm suit in the winter, and a 3 mm in the summer. Commonly they last less than 45 minutes in the water in winter before having to get out and warm up. I’d rather be warm during the entire dive. The first time I dove with this suit I stayed in water of about 9 degrees C for well over an hour, and I was warm when I came out. For maybe the first time ever I did not get out of the Pacific because I was cold, but because I was done diving.

Attention to detail

When I get new gear, I always inspect the fragile parts of the material. In wetsuits, those are the edges and the seams (especially where three pieces of neoprene meet). I was happy to see that Azure Passion puts an extra patch of thin neoprene over the most fragile parts of their wetsuits, the triple connections in the armpit (see the photos below). This extra patch helps to prevent the common pinholes in the armpit that will get water into your suit when you stretch your arms overhead. Along the lower edge of the upper part of the wetsuit, and in the crotch and on the beavertail is a glued fabric. This avoids the wearer ripping their wetsuit apart when they try to take it off.

Price and comparison to other wetsuits

This custom wetsuit retails for 250 EUR + shipping costs from Greece. Considering the quality of the wetsuit and the excellent fit this is a competitive price. It compares very well to my unfitted 3 mm wetsuit (240 USD) which was cheaper, but allows a lot of water to come in along my back, and doesn’t keep me warm as well. I have a 5 mm custom wetsuit that does not fit as well and I think was fabricated with a cheaper neoprene and within 2 years has dwindled down to 3 mm (250 USD). In short, Azure Passion holds up very well compared to the wetsuits I have used and seen so far and is great value.

The person I was in touch with about my wetsuit was responsive and helpful (we communicated by e-mail). The suit was shipped approximately 2 weeks after ordering, and arrived another 10 days or so later (shipping within Europe).

Find them online:

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Freediving fins: bi-fins, the monofin, hyperfin, Lunocet and DOL-fin monofins

Maybe you used ancient scuba fins (short bi-fins like in the above photo) when you did your first dive, or maybe you bought a cheap pair of bi-fins. When you start going down longer, deeper, and start feeling your legs burn on the way up it may be time to rethink your propulsion and get a proper pair of freediving fins. There are many options, from plastic bi-fins to carbon monofins to aluminum DOL-fins. Here are some of the things to consider when you buy a new fin, or pair of fins.

What are you using your fin for and where are you using it?

If you are spearfishing, you are going to have very different requirements from a fin than if you are purely doing competitive depth dives. Depth divers do not need the agility that spearfishers need, and are fine if they can just go up and down in a straight line. Spearfishers (and harvesters) need to be able to navigate kelp forests, reefs, occasional overhead environments and therefore need different gear. You will not commonly see a spearfisher with a monofin, although I have heard of one with an Orca Dol-fin. Spearfishers and recreational divers nearly always have a pair of bi-fins.

Also think of the water temperature when you are buying fins. In Canada, we dive with at least a three millimeter neoprene sock, more often with a 5 mm. This will mean you need to get a different size. In the tropics, you might be fine without neoprene socks.

Monofins and hyperfins are good for depth diving. A hyperfin is a monofin with a blade that is angled with respect to the foot pockets, and usually with reinforced edges (so not merely a triangular plastic, composite, or carbon flap). Consider a hyperfin an upgraded version of a monofin. Hyperfins and monofins are more efficient than bi-fins and require an all-body motion in order to get a good kick. They work optimally under a very narrow range of kicking amplitude, and are not great for surface swimming. Again, not a problem if you are a depth diver, but it may be problematic when spearing or sub-optimal when doing recreational dives. Another important difference with bi-fins is that you will not be as good of a buddy in a monofin. Helping an unconscious person in the water is much easier with bi-fins

Recreational divers are in between the demands of a depth diver and a spearfisher. They like to navigate rock reefs and overhead environments, so need more agility than a depth diver. However, they do not need to be worried about entanglement the way a spearfisher does. Recreational divers can use any type of fin but most commonly use bi-fins.

The safety diver in the foreground uses bi-fins, the diver uses a hyperfin. Photo from Jahyem, CC BY
The safety diver in the foreground uses bi-fins, the diver uses a hyperfin. Photo from Jahyem, CC BY


Freediving fin materials

Fins come in different materials. The cheapest and sturdiest is plastic. It is unfortunately very inefficient. Composite or fiberglass is one step up, and is a bit lighter and more expensive. Then comes carbon. A good fin is carbon and you should be able to buy it with different blade strengths. The blade should not bend more than about 45 degrees at normal kicking strength (with any material), so make sure you buy a blade stiffness that is adequate for your leg strength. If your fin bends too much or too little it loses its force and you will lose efficiency. If you are fairly light and have not got a lot of strength in your legs get a light blade. If you are heavy and muscular, get a stiff blade.

Hydrofoils: the future is here

[Edited in light of new information in December 2015] A foil is a wing shaped object, and a hydrofoil is a wing shaped object to be used underwater. Hydrofoils like DOL-Fin monofins and the Lunocet do not bend themselves (though I think the flukes of a lunocet do), a large difference from bi-fins and mono-fins. Rather, they depend on a suspension system that allows the blade to change angles. Both the DOL-Fin monofins and the Lunocet can be disassembled in order to make them easy to transport.

DOL-fin monofins

The foil of the DOL-Fin is aluminum. The DOL-Fin Orca model has a foot binding strap system and fairing to streamline your feet for better swimming performance. It also has added buoyancy, which will keep you horizontal during your breathe-ups. The DOL-fin X-20 and Pilot are used with biking shoes, and this may be a good option for those with difficult feet (like me). The creator of the Orca DOL-fin (Ron Smith, see below) is working on different sizes. I know a few owners of the DOL-fin Orca and they are very happy with not only the product, but also the customer service. You can find more information on its performance at

The Orca Mk 1 and its proud creator.

The Orca Mk 1 and its proud creator.


And the improved version; the Orca Mk 2
And the improved version; the Orca Mk 2

The Lunocet

The Lunocet is the first biometric monofin available, modeled after a dolphins’ tail. The Lunocet is used with biking shoes and has a sophisticated suspension system that can be set to three different resistances. It can be disassembled to a smaller package than DOL-fin monofins (which have one long hydrofoil) because of the two separate flukes. It is competitively priced at 399 USD. This price is similar to that of carbon-blade bi-fins and monofins.

When I initially did my research for the Lunocet and asked around in Facebook Groups and forums it seemed like the customer service was not up to standard. I heard stories of backorders and orders that were not fulfilled. After speaking with the current distributor of the Lunocet, Jeff Watson, I found out that the distribution of the Lunocet changed hands in November 2014. Jeff understands that the manufacturer still has some of his own back-orders to fulfill from before November 2014, when Ted Camillio (the designer of the Lunocet) fulfilled his own orders directly. However, from November 2014 onwards Lunocets have been delivered worldwide and in a timely fashion, according to testimonials on, the new distribution channel. The testimonials are sourced from social media and some testimonials are from verified reviewers meaning that these are real people, with real social media accounts)


The Lunocet

Pros and cons of different fin types

Bi-fins (80 – 200 USD for plastic or composite, 200 – 600 USD for carbon). Pros: versatile, agility, ease of transport. Cons: not as efficient as other options. Brand options: Mares, Cressi and Omer are sold in many online stores.

Monofins and Hyperfins, 150 – 300 USD for plastic, composite and fiberglass. 200 – 800 USD for carbon blade. Pros: Cheapest option specific for depth diving. Hyperfins are upgraded monofins with footpockets angled w.r.t. the blade. Cons: not good for surface swimming, only one amplitude. Brand options: Leaderfins, Waterway, and many more.

DOL-fin monofins (599 – 1200 USD). Pros: Extremely efficient, good for both depth and recreational diving. There are three types available. Indestructible compared to other fins. Can be disassembled. Cons: Heavy, not very good for penetration or kelp forests, expensive.

Lunocet (399 USD). Pros & cons? Please leave a comment!

personal experience

I used Cressi short bi-fins (scuba fins) for the first year that I dove. I did my first 30+ m with these, but after a while did want a better fin. I opted for Cressi Gara Professional bi-fins, made of plastic. They were better, but not as much of an improvement as I hoped (they were also the cheapest I could find: 80 USD). I did my first 40 m dive with these fins, but would get burning legs on any deep dive. I have only used monofins for pool practice, and never liked them very much. Then I switched to an Orca DOL-Fin Mk 1. A second hand modded with extra buoyancy, this fin was a project fin when I bought it and made me feel like a drowning caterpillar the first time I used it. After some additional mods and some practice it boosted my diving like nothing else. My bottom time has increased and my average operating depth has increased. I have not had burning legs coming up after any dive, while diving repeatedly to 30 meters. An additional advantage is that the Orca has added buoyancy, making for an extremely relaxed breathe-up. However, I am not as fast as a buddy and I have been a bit stuck in a kelp forest once. I have entered overhead spaces and as long as they are wide enough, it works well. For spearfishing around reefs, harvesting, and tight spaces I would not use the Orca but revert to bi-fins.

My only personal recommendation: spend as little as you can on your first pair of fins. Find out what you want in a year or two of diving and then go all out.

I had no financial incentive for writing this article. What is your experience with different fins? Leave a comment or start a topic in the gear forum.