Mouthfill (freediving equalization at depth)

The mouthfill is a method used to equalize your ears during deep dives. It works by moving air from your lungs into your mouth before the pressure becomes too high. You use this technique once your chest reaches the residual volume limit. Most freedivers start practicing this between 30 m and 40 m depths. It allows for much deeper descents because you no longer rely on lung air.

Don’t wait until it hurts. Many divers fail because they try to pull air from compressed lungs too late. You must trap the air in your cheeks while you still have volume. This requires practice at 20 m in a calm pool or controlled ocean setting. If you feel any pain, stop immediately. Practice this technique with a safety diver present during every session.