A leaking mask ruins dives. You stop every few minutes to clear it, you burn air doing so, your buoyancy wanders while you tilt your head back, and instead of watching the reef you spend the dive managing a piece of silicone. The frustrating part is that almost every leak comes from one of five causes, and every one of them is fixable — usually without buying anything. Here is what actually goes wrong and how to put it right.
Why Masks Leak in the First Place
A diving mask does not seal because the strap holds it on. It seals because a soft silicone skirt lies flat against your skin all the way around, and the small pressure difference between the inside of the mask and the surrounding water presses that skirt into place. The strap does nothing more than stop the mask sliding off your face.
That single fact explains most leaks. Anything that lifts the skirt away from the skin at any point around its perimeter opens a channel — a stray hair, a fold of neoprene hood, a strap pulling the frame off-centre, a moustache, or an overtightened strap distorting the silicone. Water does not need a gap you can see. A channel a fraction of a millimetre wide is enough to give you a steady trickle across the dive.
Work through the five points below in order. In our experience the vast majority of chronic leakers are solved by the third one, and almost none by buying a more expensive mask.
1. Start With a Skirt That Can Actually Seal
Masks look similar in the rack, but the silicone varies enormously. Good liquid silicone is soft, slightly tacky to the touch, and springs back instantly when you stretch it. Cheaper blends feel firm and rubbery straight out of the box, and they only get worse — they harden with UV exposure and salt until they can no longer conform to the contours of a face at all.
Look specifically for a double-feathered sealing edge: two thin lips of silicone around the perimeter rather than one thick one. The outer lip takes the load and the inner one follows the fine detail of your skin, and the pair tolerates far more facial movement before letting water past. Almost every mask that seals reliably over years has this.
The other thing worth checking is where the buckles are mounted. Buckles fixed to a rigid frame force the strap to pull at whatever angle the frame dictates. Buckles mounted on the skirt itself pivot, so the strap finds its own natural angle and does not twist the seal. If you are shopping now, our full guide to choosing a diving mask covers lens configuration, volume and fit in detail, and you can browse single-lens, twin-lens and multi-window masks to see the differences side by side.
2. Get the Size Right for Your Face
Masks are shaped for face families, not for an average. Nose bridge height, cheekbone width, the distance between the eyes and the depth of the groove above the upper lip all vary, and a skirt cut for a broad face will bridge across a narrow one at the temples every time. No amount of adjustment fixes a shape mismatch.
The test takes ten seconds and every dive shop expects you to do it. Hold the mask against your face with the strap hanging loose in front of the lens, so it cannot pull the skirt into an artificial seal. Inhale gently through your nose, then take your hands away. The mask should stay put on its own for several seconds.
Then do the part most people skip: move your face. Smile broadly, talk, raise your eyebrows, clench your jaw as you would around a regulator mouthpiece. A mask that holds a static seal but breaks when you smile will leak every time you communicate with your buddy. Check too that the top edge sits on your forehead and not up on your hairline, and that the bottom edge clears the top of your lip.
Watch for masks that are too small as well as too large. If the skirt is pressing hard enough to leave deep red marks or bruising around the eyes after a dive, the mask is undersized for your face, and it is being held in a seal by tension rather than by shape — which fails as soon as you move.
3. Keep Hair, Hood and Straps Out of the Seal
This is the single most common cause of a leaking mask, and it accounts for most of the cases where a mask that sealed perfectly in the shop leaks on the boat. A single hair lying under the top edge of the skirt is enough to hold it a fraction of a millimetre off the skin, and water follows the hair in like a wick.
Before every dive, sweep your forehead hair back with your fingers and hold it clear while you seat the mask. Long hair needs to be properly tied. If you are wearing a neoprene hood, run a finger all the way around the perimeter of the skirt after donning and confirm that the silicone is resting on skin, not on the hood edge — the front edge of a hood is the classic offender, and it is invisible to you and obvious to your buddy.
Check the mask strap itself is not trapped under the skirt at the temples, and that a snorkel keeper or a camera lanyard is not pulling on the frame from one side. Anything that applies asymmetric force will open the seal on the opposite corner.
4. Centre the Mask and Position the Strap Properly
A mask worn slightly off-centre seals on one side and gapes on the other, and because the gap is small you often will not notice it on the surface. Seat the mask deliberately: nose in the pocket, skirt even on both cheekbones, then bring the strap over. Do not pull the mask into place by the strap.
Strap height matters more than people expect. Too high and it pulls the bottom edge of the skirt away from your upper lip; too low and it slides down the back of the skull during the dive, dragging the top edge open. The strap should sit at the widest part of the back of the head, roughly level with the middle of the mask. Split straps that fork above and below that point are noticeably more stable than a single band.
A neoprene or lycra strap cover helps here, and costs very little. It stops the silicone pulling hair, spreads the load across a wider area so the strap does not migrate, and makes the mask far easier to adjust with cold hands or thick gloves. You will find them alongside spare buckles and straps in mask accessories.
5. Stop Overtightening the Strap
When a mask leaks, the instinctive response is to pull the strap tighter. It is almost always the wrong move, and it is the reason a lot of divers never solve their leak.
Excess strap tension pushes the mask frame into your face and deforms the skirt. The silicone buckles at the corners, lifts away from the skin at the temples and along the lip, and creates precisely the gaps you were trying to close. On top of that you get a pressure headache after an hour underwater and deep marks around the eyes.
The correct tension is barely more than snug — enough that the mask does not shift when you shake your head, and no more. If the mask still leaks at that tension, the cause is one of the four points above, not the strap. Loosening the strap and re-seating the mask solves a surprising number of leaks on the spot.
Working Out Where the Leak Is Coming From
If you have gone through all five points and still get water in, narrowing down the location tells you what to fix.
- Water collecting under the nose: Usually the lower skirt edge lifting off the upper lip. Suspect facial movement, a moustache, or a strap sitting too high.
- Water running in from the top: Almost always hair or a hood edge trapped under the skirt, occasionally a strap worn too low.
- Leak at one temple only: The mask is off-centre, the strap is twisted, or something — a snorkel keeper, a lanyard — is pulling from one side.
- Leak that starts only at depth: Points to a mask that seals under light pressure but has a shape mismatch that opens as the skirt compresses. Usually a sizing problem.
- Leak that appears when you look down: Check whether your regulator hose or an inflator hose is pressing against the lower edge of the mask in that position.
- Steady leak with no obvious cause: Inspect the skirt against a light for hairline splits, and check that the buckles have not cracked and let the strap slip a few millimetres during the dive.
The Moustache Problem
Facial hair on the upper lip sits exactly where the lower skirt edge needs to make contact, and no mask design solves it. The reliable fix is a thin smear of pure silicone grease worked into the moustache along the sealing line before each dive — it fills the gaps between hairs and gives the skirt a continuous surface to press against.
Use only silicone grease. Petroleum-based products such as petroleum jelly attack silicone and will degrade the skirt of an expensive mask within a season. Some divers instead trim a narrow channel in the moustache just under the nose, which works and is free. Others simply accept a slow trickle and clear the mask periodically.
Clearing a Mask Without Ending the Dive
Even a perfectly fitted mask takes on water occasionally, and being relaxed about clearing it is what separates a minor interruption from a spoiled dive. Tilt your head back slightly, press the top edge of the frame against your forehead with two fingers, and exhale steadily through your nose. The air displaces the water downward and out under the bottom edge of the skirt. Pressing the bottom of the mask instead is a common beginner error and traps the water in.
Practise it in shallow water until it is automatic, including a full flood-and-clear. A diver who can clear a mask without thinking treats a leak as a nuisance; a diver who cannot treats it as an emergency, and that is where dives get cut short and ascents get rushed.
Care That Prevents Leaks
Most masks that start leaking after a few seasons have stiffened rather than broken. Salt crystallises in the silicone and abrades it from the surface inward, and UV hardens it. Rinse the mask in fresh water after every single dive, not just at the end of a trip, and let it dry in shade rather than in the sun. Those two habits do more for long-term sealing than anything else.
Store the mask in a rigid box. Loose in a gear bag, a skirt spends months folded against a tank valve or a weight and takes a permanent set in that shape — a crease across the skirt is a leak channel that no adjustment will close. Avoid storing a clear skirt pressed against black neoprene for long periods, as the dye can migrate into the silicone.
Inspect the strap and buckles at the start of each season. Silicone straps develop fine cracks at the buckle slots long before they snap, and a buckle that has gone brittle will let the strap creep loose mid-dive and open the seal without you understanding why. Both are cheap consumables and both are worth replacing on sight rather than after failure. If your mask is more than a few years old and the skirt has become glossy and firm rather than matte and soft, the silicone has aged out and no amount of technique will restore a reliable seal.
FAQ
Why does my mask leak even though it passed the suction test?
The suction test only confirms a static seal on a still face. Most real leaks come from movement or obstruction: hair or a hood edge under the skirt, smiling and talking around the regulator, an off-centre mask, or a strap that has crept out of position. Repeat the test while smiling and talking, and run a finger around the full perimeter after donning to check the skirt is on skin all the way round.
Should I tighten the strap if my mask leaks?
No — it usually makes it worse. Overtightening deforms the skirt and lifts it away from the skin at the corners, creating new gaps while giving you a pressure headache. The strap only stops the mask sliding off; the seal comes from the skirt lying flat against your face. Loosen it until the mask is merely held in place, then look for the real cause.
Do I have to shave my moustache to dive?
No. A thin layer of pure silicone grease worked into the hair along the sealing line fills the gaps and lets the skirt seal against a continuous surface. Never use petroleum jelly or other petroleum-based products, which degrade silicone. Trimming a narrow channel directly under the nose is a free alternative that also works.
Can a hood cause a mask to leak?
Frequently, and it is one of the least obvious causes. The front edge of the hood ends up under the top or side of the mask skirt where you cannot see or feel it. After donning both, run a finger all the way around the outside of the skirt and confirm silicone is touching skin, not neoprene. Hoods cut with a scalloped face opening are designed to reduce this.
Is a more expensive mask less likely to leak?
Not necessarily. Price buys better silicone, better glass and better buckles, all of which help durability — but a cheap mask that matches your face shape will seal better than an expensive one that does not. Fit is decided by shape, and shape is not correlated with price. Try before you buy, and treat the suction test as the deciding factor.
How do I clear water from my mask underwater?
Tilt your head back a little, press the top edge of the mask frame against your forehead, and exhale steadily through your nose. The rising air pushes water down and out under the bottom of the skirt. Press the top, not the bottom — pressing the bottom seals the exit and traps the water. Practise a full flood-and-clear in shallow water until it needs no thought.
Why do I have red marks around my eyes after diving?
Either the strap is too tight or the mask is too small for your face. Deep marks and bruising mean the skirt is being pressed into the skin rather than resting on it, which is uncomfortable and, counter-intuitively, makes leaks more likely because the deformed silicone lifts at the corners. Loosen the strap first; if the marks persist at minimal tension, the mask is undersized.
Can a leaking mask be repaired?
Straps and buckles are replaceable and cheap, and replacing them fixes leaks caused by slipping or a broken buckle. A skirt that has hardened with age or taken a permanent crease cannot be restored — silicone does not soften again once it has degraded. At that point the mask has reached the end of its service life, and no technique or grease will give you a reliable seal.