Intermediate 9 minutes
Barotrauma: ears, sinuses, lungs, teeth, and mask
Any air space that can't equalize pressure ends up getting injured
Water doesn't squeeze selectively: it compresses your whole body equally. What happens is that almost all of your body is liquid and doesn't mind. The problems concentrate exactly in the few places where you're carrying air.
In this article you'll see what barotrauma is, why some forms appear on descent and others on ascent, how the ones affecting the middle and inner ear, sinuses, lungs, teeth, mask, and drysuit manifest, and what prevention technique applies to each.
Ear barotrauma is by far the most common diving injury, and also the one that ruins the most dives and keeps the most people out of the water for weeks. Nearly all of it is preventable with technique and one decision: don't force it. This article is educational material and doesn't replace medical evaluation; if you have persistent pain, hearing loss, or vertigo after diving, you should consult a professional.
The mechanism, and why there are two moments of risk
Barotrauma is an injury caused by a pressure difference that couldn't be equalized.
The body's air spaces (the middle ear, the sinuses, the lungs, the occasional dental cavity) and the ones your gear creates (the mask, the drysuit) are connected to the outside more or less efficiently. As long as the connection works, gas moves in or out and the pressure equalizes on its own or with a bit of help. When the connection gets blocked, the space ends up at a pressure different from its surroundings, and that difference is discharged onto the tissue.
On descent, ambient pressure increases and the air space tends to compress. If no gas enters to compensate, the surrounding tissue gets pushed inward: it congests, becomes inflamed, fills with fluid, and can bleed. This is the classic "squeeze" mechanism, and it's responsible for most barotraumas.
On ascent the opposite happens: the trapped gas expands and needs to get out. If the pathway is blocked (by inflamed mucosa, by a plug, by a decongestant whose effect has worn off) internal pressure exceeds external pressure and the tissue is injured from within. This is the reverse block, less common but trickier to manage, because it happens exactly when the obvious solution, ascending, is the thing that makes it worse.
And there's a principle that runs through the whole category: relative pressure changes are greatest near the surface, as you saw in the pressure-and-depth article. The first few meters of descent demand the most equalizing, not the last ones.
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