To me, a mask is the most intimate and important aspect of our freediving equipment. It rests directly on our faces and allows us unfettered visible access into the world that we love so much.
We take our vision for granted on land and seek to have the same clarity and scope of vision underwater, all without being conscious of actually wearing facial equipment.
For freediving, a low-volume mask is of the utmost importance. All of the masks mentioned below are low to ultra-low volume. Generally, people will advise you to choose an opaque / dark skirt, so that light does not penetrate the otherwise clear silicone and reflect off the inside of the lenses.
Also of critical importance is fit - and nothing beats trying them on yourself in a dive shop or better yet, in the the water. Having said that, if you know if your face is small / narrow, medium or wide, that can help a lot with the direction below on some of the most popular and best-suited masks for freediving:
This mask is the one you will see in most freedive videos by "professionals" and serious freedivers. The lenses are plastic and this makes the mask extremely light. The lenses are curved near the periphery and as such, the vision gets a bit distorted and is unnerving to some, but the eyes quickly adapt. Vision through the plastic lenses is decent, but no where near as clear / sharp as a glass lensed mask.
The mask is very flexible, which makes it compress well with depth and doesn't require very much equalization. This also makes it quite fragile and requires care and diligent storage in a protective box.
Fits medium to wide faces well.
Aqualung / Technisub Micromask:
The Micromask is a super-low volume mask which positions the glass lenses very close to the eyes of the wearer. This increases the field of view dramatically and is why this mask is extremely popular among freedivers and spearfishermen.
Cost is generally higher on this mask them most others and as a result, several "copies / clones" have appeared on the market, including the IST M-99. The silicone on the IST isn't quite as soft as the Micromask, but is 1/2 the cost.
It fits a wide variety of faces and is particularly well-suited to small and medium faces.
The Mystic is very popular amongst spearfishermen and is gaining popularity in the freediving community. It has extremely low volume and is best characterized by the incredibly soft / compliant silicone which makes wearing it extremely comfortable to wear and does not provide the harsh mask mark / indentation that you will see on some freedivers with other masks.
The glass lenses are very close to the eyes and the vision is great.
This is currently my favourite all-round mask for recreational diving, general training, underwater hockey and underwater rugby.
Fits a variety of faces, including narrow, medium and wide due to the compliant nature of the flexible skirt.
This mask is not a new design, but not very well known or popular in North America. I recently was able to try one and I was very impressed. Very low volume and an extremely flexible silicone skirt make this very comparable in properties to the Mystic above.
It had me second-guessing my mask choice and I want to try it out again and measure the volume differences on my face before deciding to order one. You won't go wrong with either choice though. Also interesting is that if you search for a decent review online - you will only find one - but it is that of William Trubridge whom is the world record holder in CNF and a world-class diver / instructor.
I can say that it definitely fits people with narrow and medium faces well - no direct / personal experience with wide to date.
This mask began life as a set of Cressi Galileo goggles that they added a larger skirt / nose piece to. Low volume, glass lenses and poor peripheral vision characterize this mask.
It was popular in the early to mid 2000's when it first came out but we have seen its popularity wane with the top competitors, with them favouring newer style masks like the Micromask, Sphera or ditching the mask altogether in favour of liquid goggles or nothing at all. Still fairly popular in freediving club circles for line-diving because of the very low volume. Spearfishermen are not interested in this mask due to its poor peripheral vision.
Fits medium to wide faces well.
A great dual-purpose mask for snorkelling / scuba / freediving. It is low-volume, but not as low as the Micromask or Mystic, etc.
Has excellent downwards visibility (important for Scuba to check your gauges, or while snorkelling from the surface).
Fits small to medium faces. This is the mask that I lend to women or people with small faces for a guaranteed good seal.
This mask has a single glass lens and offers great visibility, yet still offers quite low volume for a single-lens mask. I believe that it is best suited for spearfishing, recreational freediving, snorkeling and scuba use. I would consider something lower volume if planning on going deeper than -30m personally.
The silicone skirt is not large, so a fairly precise fit is important.
Fits medium to wide faces well.
The Apneaddict's Modified Micromask:
Now - what do I use for depth??
Seeing as I have a narrow face and the Sphera doesn't fit me that well (and there is a lot of extra void space in it with my narrow face), I decided to modify my Micromask.
The Micromask is the mask which had the lowest amount of volume when on my face, as checked visually / estimated in the mirror.
My eyelashes touched the glass, but I noticed that there were large sections on the sides that were contributing 75% of the volume and providing peripheral vision that was not needed for depth / line-diving.
I decided that I needed to fill in that void space, with this scene from The Big Blue as inspiration:
I used a silicone putty product called Sugru to fill the void spaces that I didn't "need" for line diving.
First I cut up a credit card and use as an estimator and electrical taped it in place to verify the amount of peripheral vision vs. remaining volume that I'd end up with (didn't want to screw up a $100 mask).
When this thick, the Sugru takes several days to FULLY cure and off-gas... but it makes an awesome bond and is safe on your eyes / skin.
The result is less than 20cc of air space and incredible visibility, because my eyes are so close to the lenses. I've still got 2/3 of the visibility with only 20% of the volume!!
I added approx 50cc's of Sugru and I calculated that this would save me approx 300ml of air that I would have to otherwise put into the mask for equalization.
It turns out that there was more to the story:
I took some volume measurements by filling the mask with water and compressing it onto my face and weighing the residual:
= 52 ml when lightly fitted
= 22 ml tightly pressed
= 18.5 ml tightly pressed with nose pinched
The compressibility ratio of 2.8 would suggest no need for equalization before 18m.
My previous depth mask was the Sporasub Mystic:
= 75 ml when lightly fitted
= 51 ml tightly pressed
This was a large improvement!
I took the mask out to Tobermory for a dive session in 24m of depth available right off shore and when I fitted the mask tight, I didn't have to equalize it at all - even at the bottom. This was a pleasant surprise, but my math didn't account for it.
I then put it on at the surface very loosely and pre-equalized it before diving. It got very tight at -14m and NEEDED air by -18m (right on with my calculations!).
So what was the difference? When I wear the mask tight and scrunch my face INTO the mask before leaving the surface, my face ends up acting like a dynamic spacer and as pressure increases, my cheeks and brow gets sucked into the void and negates the need to equalize! With a plastic lensed Sphera, the mask would deform... but with this modified Micromask, it is the soft tissues of my face that is (temporarily) deforming!