Dive Illnesses and Treatments Practice Test

When you go deeper, the surrounding water pressure increases and any air spaces on your face must stay in equilibrium with that pressure. Facemask squeeze happens when the air space inside the mask doesn’t rise in pressure fast enough to match the water pressure outside. If the mask doesn’t equalize properly—due to a poor seal, a misfit, or not exhaling through the nose to vent air into the mask—the external pressure pushes the mask harder against the face, producing that tight, squeezing sensation around the eyes and nose. So the key idea is maintaining equal pressure inside the mask with the surrounding water through proper fit and timely equalization.

Wearing goggles doesn’t create this same facial air-space squeeze, air trapped in a dry suit leads to suit squeeze around the body, and dehydration isn’t a mechanism that causes a mask squeeze.