- + Published internal volume of 85 cm³
- + Two tempered glass lenses, tilted for downward visibility (Cressi)
- + Swivel buckles with micrometric adjustment
- + Eight colour combinations, including clear skirts
- − No corrective lens option listed by Cressi America
- − No published weight
- − Two lenses mean a frame bar between the eyes
Overview
This roundup compares three freediving masks on what their makers publish: lens count, internal volume, weight, intended use and US list price. Fit cannot be read from a spec sheet, so every pick comes with the same advice: do the no-strap seal test on your own face before you dive. The Cressi Nano leads because it is the only one with a published volume.
Why Freediving Masks Are Different
The defining feature of a freediving mask is low internal volume: the air space between the lens and your face. Water pressure rises by about one atmosphere for every 10m (33ft), so absolute pressure is 2 atmospheres at 10m. To stop the mask pressing into your face (mask squeeze), you breathe a little air out through your nose into it. Keeping a mask at full size takes about one extra mask volume of surface air for every 10m of depth.
Few makers publish that volume. Cressi gives 85 cm³ for the Nano, which works out to roughly 85 ml of air by 10m, 170 ml by 20m and 255 ml by 30m. Mares describes the Mares Sealhouette as minimal volume without a number, and Hollis does the same for its M1, as the Hollis M1 freediving breakdown shows.
What to Prioritize
Skirt Seal
Nothing else matters if the skirt does not seal. A leaking mask needs constant clearing and lets water into your nose on the way down. Test the seal before buying: place the mask against your face without the strap and inhale through your nose. It should hold for several seconds without hand support.
Internal Volume
Lower is better for depth work, because the cost grows by one mask volume of air for every 10m. Near the surface the difference between masks is small. For deeper training, a published figure lets you compare masks; the guide to low-volume freediving masks covers how to estimate one at home, and every milliliter you do not spend on the mask is left for equalization of your ears.
Lenses
All three masks here have two lenses. Cressi specifies tempered glass for the Nano. Mares does not state the Sealhouette's lens material on its product page, and Mares lists no optical lenses for it. Omer offered graduated lenses for the Alien. If you need a prescription, check that the maker sells corrective lenses for the exact model.
Fit: What the Makers Say
- Cressi Nano
- Cressi makes no face-shape claim.
- Mares Sealhouette
- Mares lists the fit as Regular, with no mention of face width.
- Omer Alien
- No fit claim in any source checked.
- What this means
- Fit depends on your face, and no spec sheet settles it. Do the no-strap test on each mask you consider.
The Picks in Short
- Cressi Nano
- Published 85 cm³ volume, two tilted tempered glass lenses, $89.95 US list.
- Mares Sealhouette
- Double lens, 161 g, Regular fit, minimal volume with no figure, $83.95 US list.
- Omer Alien
- Two removable lenses with an optical lens option, 160 g; confirm stock, as Nootica lists it as discontinued.
Best Overall: Published 85 cm³ Volume
Cressi Nano Mask
Cressi
$89.95
- Lenses
- Two, tilted, tempered glass
- Volume
- 85 cm³ (Cressi)
- Frame
- Thin, Integrated Dual Frame
- Skirt
- Silicone
The only mask in this roundup whose maker publishes an internal volume: 85 cm³. Cressi sells it for advanced freediving and spearfishing, with two tilted tempered glass lenses, a thin frame and swivel buckles with micrometric adjustment. US list is $89.95, or $109.95 with mirrored lenses (Cressi America, October 2026).
- Published internal volume of 85 cm³
- Two tempered glass lenses, tilted for downward visibility (Cressi)
- Swivel buckles with micrometric adjustment
- Eight colour combinations, including clear skirts
- No corrective lens option listed by Cressi America
- No published weight
- Two lenses mean a frame bar between the eyes
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Double-Lens Alternative: 161 g
Mares Sealhouette Mask
Mares
$83.95
- Lenses
- Double lens
- Volume
- "Minimal" (no figure)
- Weight
- 161 g
- Fit
- Regular (Mares)
Mares sells the Sealhouette as a spearfishing mask with a double lens, a silicone skirt and strap, low-profile buckles on the skirt and a reduced distance between lens and eye. Mares describes the volume as minimal but gives no figure, lists the weight as 161 g and the fit as Regular. US list is $83.95 (Mares, October 2026).
- 161 g, per Mares
- Low-profile buckles positioned on the skirt
- Silicone skirt and silicone strap
- No internal volume figure published
- No optical lens option (Mares: visual aids, no)
- Fit listed only as Regular
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Optical Lens Option: Check Stock First
Omer Alien Mask
Omer
See current price
- Lenses
- Two, removable
- Volume
- Not published
- Weight
- 160 g
- Skirt
- Black silicone
A two-lens spearfishing mask with removable lenses, for which Omer offered graduated lenses. Apnea Passion gives its weight as 160 g. Omer called it low volume, but no source checked gives a figure, Omer's site is offline, and the retailer Nootica lists it as discontinued, so confirm stock before ordering.
- Removable lenses, with optical lenses offered by Omer
- 160 g (Apnea Passion)
- Buckles mounted on the skirt
- No internal volume figure in any source checked
- Listed as discontinued by Nootica; Omer's site is offline
- No US list price could be verified
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