Sherwood Ceto Mask

Hold the mask against your face without using the strap, look slightly down, and inhale gently through your nose; a well-fitting mask holds itself in place for a few seconds. Check that the skirt seals all the way around without digging into the nose bridge, and that there are no gaps at the temples or above the upper lip. A mustache can break the seal even on an otherwise well-fitting mask.

New masks carry a residue on the inside of the lens left over from manufacturing, and defog cannot stick to it, so the mask fogs until that film is removed. The standard pre-treatment is to scrub the inside of the lens with a mild abrasive cleaner or a dedicated mask prep and rinse thoroughly, repeating if it still fogs. Follow the mask manufacturer's instructions, particularly on coated or mirrored lenses.

Apply defog to a dry lens before the dive, spread it over the whole inner surface, then rinse briefly with water just before you put the mask on. Fogging happens when warm moist air meets a cooler lens, so a clean lens with a thin surfactant film is the fix. Keep sunscreen off your fingers before handling the inside of the lens, because that film fogs badly and is hard to remove.

Dive mask lenses should be tempered safety glass because it resists scratching and, if it ever does break, fractures into blunt granules rather than sharp shards next to your eyes. Untempered or plastic lenses scratch easily and can craze, which is why tempered glass is standard on scuba masks. Look for the tempered marking etched on the lens.

Yes, prescription options are widely available, usually as masks fitted with stock corrective lenses in set diopter steps, custom-ground lenses installed in compatible frames, or bonded lenses added to an existing lens. Not every mask frame accepts replacement lenses, so check compatibility before you buy the frame. An optician or a dive shop can help translate your glasses prescription into a mask lens choice.

Rinse it in fresh water after each dive day and let it dry away from direct sunlight, avoiding anything abrasive on the treated inner lens. Store it in a rigid mask box so the skirt is never compressed or creased, since a set crease in the skirt is a permanent leak. Keep silicone skirts away from petroleum products and prolonged UV, both of which yellow and harden them.

Not tight at all in the usual sense, because over-tightening is the most common cause of both leaks and headaches; a hard-pulled strap distorts the skirt and lifts the seal off your face. The strap should sit high on the back of your head and be just firm enough to keep the mask from shifting. If you need it cranked down to stop a leak, the mask does not fit your face.

Only the Tangine and Rubicon versions use color-enhancing lenses. The Tangine lens reduces light wavelengths from 400 to 600 nanometers to minimize glare and improve optical clarity, and the Rubicon lens filters out blue wavelengths to add optical contrast. The Black, White, Tiffany, Magenta, Blue and Yellow versions are silicone color choices fitted with standard tempered lenses, so the view through them is uncolored.

They target different light conditions. Tangine cuts light wavelengths in the 400 to 600 nanometer range, which minimizes glare and improves optical clarity. Rubicon filters out blue wavelengths and adds optical contrast, which Sherwood describes as ideal for low light levels or night diving. Pick Tangine for glare control and Rubicon for contrast when light is limited.

Frameless means there is no rigid outer frame around the single lens. The Ceto uses a double feathered edge soft silicone skirt for the face seal.

Sherwood does not publish a prescription or corrective lens option for the Ceto. If you need corrective vision underwater, call DiveCatalog at 888-701-4017 or start a chat and we will point you to mask models that accept stock diopter or custom-ground lenses.