Mask Squeeze and Sinus Squeeze: Causes and Prevention
Mask squeeze leaves red eyes and a bruised face; sinus squeeze hurts in the forehead or teeth. What causes each, how to prevent them, and when to see a doctor.
Mask squeeze happens when you don’t add air to your mask on the way down. The air inside compresses, the mask presses into your face, and the low pressure pulls on the soft tissue around your eyes, sometimes leaving bloodshot eyes and light bruising. Sinus squeeze is the same pressure problem in the air spaces inside your skull: a blocked sinus can’t equalise, and you feel sharp pain in your forehead, cheeks or upper teeth. Both are largely preventable. Breathe a little air into your mask as you descend, and don’t dive with a blocked nose.
The first one is a classic beginner souvenir. The second is your body telling you to stay out of the water today.
What causes mask squeeze
Your mask is an air space like any other. By 10 metres the air in it has been squeezed to about half its surface volume, as our post on pressure and Boyle’s law explains. The only way to top it up is through your nose, which is why a freediving mask covers it.
Most beginners concentrate so hard on their ears that they forget the mask entirely. With every metre the suction on the face grows. You feel the mask press into your cheeks and the bridge of your nose, then a pulling sensation around the eyes.
If it goes far enough, small blood vessels give way. The usual results are:
- red patches of blood across the whites of the eyes
- tiny red dots or light bruising on the skin around the eyes
- a puffy face for a few hours
It is dramatic to look at and usually painless. Expect questions at work on Monday.
How to prevent mask squeeze
- Exhale into the mask. Every few ear equalisations, let go of the nose pocket and breathe a small puff of air out through your nose. You will feel the mask lift off your face slightly.
- Use a low-volume mask. Less air inside means less air needed to equalise it. That matters deeper, where every bit of lung air is precious. Our freediving mask guide explains what to look for.
- Make sure it fits. A mask that leaks tends to get over-tightened, and then you stop paying attention to it. If you have a moustache, check that it isn’t breaking the seal under your nose; some divers trim the top edge before a trip.
- Leave swimming goggles in your bag. They cover only the eyes, so you can’t add air to them. Fine for laps, not for duck dives.
If you need vision correction, the answer is a prescription lens in a proper mask, not goggles. Our guide to prescription freediving masks covers the options.
What to do if you get mask squeeze
Most cases settle on their own over days to a couple of weeks. Stop diving for the day and give your face a rest. See a doctor or eye specialist promptly if your vision is blurred or different, your eye hurts, the redness spreads or doesn’t fade, or you take blood-thinning medication. Don’t start using eye drops without medical advice.
What causes sinus squeeze
Your sinuses are air-filled spaces in the bones of your face and skull. The main ones are the frontal sinuses in the forehead, the maxillary sinuses behind the cheekbones, the ethmoid sinuses between the eyes, and the sphenoid sinuses deep behind the nose. Each connects to the nasal cavity through a small opening.
Normally you don’t have to do anything to equalise them. The air in your nose is at the same pressure as the water around you, and it flows in and out of the sinuses by itself. Problems start when those openings narrow or block. A cold, an allergy, a flare-up of long-term sinusitis, polyps, or swelling from dust and pollution can all seal a sinus off. The air inside can’t equalise, the pressure inside falls behind the pressure around it, and the lining swells and can bleed.
Sinus squeeze tends to show up early, often in the first few metres, because that is where the relative pressure change is largest. If your forehead starts to ache at 3 metres in the pool, that is not something to push through on the way to 10.
Symptoms of sinus squeeze
| Where it hurts | Sinus usually involved | Notes |
|---|---|---|
| Forehead, above the eyes | Frontal | Commonly affected in divers |
| Cheeks, upper back teeth | Maxillary | Can feel like toothache |
| Between or behind the eyes | Ethmoid | Often with a stuffy, blocked feeling |
| Deep headache, top or back of the head | Sphenoid | Less common |
Other signs include blood or bloody mucus in your mask or nose after surfacing, and a feeling of pressure that lingers after the dive. On the way up, a blocked sinus can also cause trouble in the other direction, which is called a reverse block.
When to stop diving and when to see a doctor
Stop at the first sinus pain. Rise until it eases, then end the dive. If it has happened once, the lining is already irritated and the next dive will usually be worse, so end the session too.
Safety: Never push through face, forehead or tooth pain on a descent. See a doctor if sinus pain lasts more than a day or two, or if you have a fever, thick discoloured discharge, swelling around the eye, changes in vision, a severe headache or nosebleeds that won’t stop. If sinus squeezes keep happening on easy dives, ask for an ENT check.
An ENT can look for structural causes such as a deviated septum or polyps, and help you manage allergies properly over time. That is a far better plan than finding ways to dive through it.
Preventing sinus squeeze
- Don’t dive congested. If you can’t breathe easily through both nostrils, you are not diving today. Our post on freediving with a cold explains the risks.
- Don’t use medication to make a dive possible. Decisions about decongestants or allergy treatment belong with your doctor, not your dive schedule.
- Descend slowly in the first metres. That is where pressure changes fastest, and where you will notice trouble early enough to stop.
- Know your triggers. If dusty winters, pollen season or AC-dried offices leave you blocked, talk to your doctor well before a trip rather than the night before.
A two-minute mask check before you get wet
Put your mask on at home, pinch through the nose pocket as if equalising your ears, then let go and breathe a tiny puff out through your nose. Feel the skirt lift slightly off your face. Do it ten times until it is automatic, then repeat the habit in the pool every few equalisations. While you are at it, close one nostril at a time and check you can breathe freely through the other. If one side is blocked, give the session a miss.
The freediving.in community is coming soon. Stay tuned.
Frequently asked questions
How long do red eyes from mask squeeze last?
Blood in the white of the eye from mask squeeze usually fades over a week or two, sometimes longer, often turning yellowish like a bruise as it clears. It typically looks far worse than it feels. See a doctor or eye specialist promptly if your vision changes, your eye hurts or the redness isn't improving, and mention it if you take blood-thinning medication.
Can you freedive with swimming goggles?
Not below the surface for long. Swimming goggles cover only your eyes, so you cannot add air to them through your nose, and within a metre or two they start to squeeze. That can cause the same burst blood vessels as mask squeeze. Use a proper mask that covers your nose. Fluid-filled goggles exist for advanced divers but are a specialist tool.
Why is there blood in my mask after a dive?
Usually it is a small nosebleed from a sinus squeeze or irritated lining inside the nose, often on a day when you were slightly congested. It is common and usually minor, but it is a clear signal to stop diving for the day. If bleeding is heavy, keeps returning, or comes with severe pain, fever or ear symptoms, see a doctor.
Can sinus squeeze cause tooth pain?
Yes. The roots of the upper back teeth sit close to the maxillary sinuses, so a squeeze there can feel like toothache. Tooth pain while diving can also come from air trapped under an old filling or crown, known as barodontalgia. If tooth pain keeps coming back on dives without any sinus symptoms, see a dentist.
