Squeeze — What It Is and Why It Matters
Squeeze is the compression of a gas-filled body space or equipment space caused by increasing water pressure during descent. When the pressure outside the space is greater than the pressure inside, the tissues or flexible walls of the space are pushed inward, causing discomfort or injury. Equalization — adding air to the space — relieves the squeeze.
Common types of squeeze include ear squeeze (middle ear), sinus squeeze, mask squeeze (the most visually dramatic, causing facial bruising and bloodshot eyes), and suit squeeze (in drysuits). Ear squeeze is by far the most frequent and the most common reason divers abort a descent. Equalizing early, often, and before pain occurs is the key to prevention.
Frequently Asked Questions
How do I prevent ear squeeze?
Begin equalizing before you feel any pressure, then equalize every meter or so during descent. Descend feet-first to keep the Eustachian tubes oriented favorably. If you feel pain, stop descending, ascend slightly until the pain resolves, then try again gently. Never force equalization.
What is mask squeeze?
Mask squeeze occurs when you forget to exhale through your nose into the mask during descent. The increasing water pressure pushes the mask against your face, which can cause bruising around the eyes and, in extreme cases, subconjunctival hemorrhage (bloodshot eyes). It is entirely preventable by periodically exhaling a small amount into the mask as you descend.
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