As scuba divers, free divers and snorkelers go deeper underwater, water pressure increases and presses against the air spaces in the skull, particularly those inside the ears. One of the basic skills that needs to be mastered to go deep underwater safely is equalization, or forcing more air into these spaces so that the air pressure matches the water pressure.
The most common method taught for equalizing pressure is the Valsalva maneuver. To perform this, you simply clamp your nose shut with your fingers and exhale through the nose. Another that is almost as common is the Toynbee maneuver. The core of Toynbee is swallowing, and although it works best when you clamp your nose shut, it still has some effect if you swallow without clamping. A practical problem with the Toynbee maneuver encountered by some scuba divers is getting enough saliva in their mouth while breathing compressed air to make a proper swallow. A way around this is to swallow a little sea water instead. Other maneuvers are making a chewing motion, pushing the jaw forward or raising the base of the tongue. The degree to which a particular method is effective can vary, because everyone is a little different. While most people do just fine with Valsalva, some find it only marginally useful and swear by Toynbee. Most find chewing or raising the tongue to be of limited value, but a few lucky divers do a great job equalizing using those methods.
Mastering the basic techniques of equalization is pretty easy, but applying them in practice is a little trickier. A diver needs to equalize steadily on the way down. If you fail to keep pace with the water pressure as you descend, the result will be steadily increasing pain on the ears. Also, if the water pressure becomes substantially greater than the air pressure inside your head, you will find it difficult or impossible to push more air into the spaces in your ears. The harder it becomes to equalize, the more you risk injuring yourself if you try do so. Never try to blow down hard in the Valsalva maneuver, for example. Instead, ascend a bit and try to equalize where the pressure isn't so great.
Another pocket of air that needs to be equalized is your dive mask. To not do so will mean at least mean a case of "mask face," or a slightly painful and very obvious impression left behind on the skin of your face by having the mask pushed hard against it for half an hour or more. On deep dives, the pressure might crack the mask lenses. Equalizing the mask is even easier than equalizing your ears, however. Simply exhale through your nose. That will put more air into the dive mask, and any excess air will leak out from under the mask's skirt as micro-bubbles.
Article Written By Edwin Thomas
Edwin Thomas has been writing since 1997. His work has appeared in various online publications, including The Black Table, Proboxing-Fans and others. A travel blogger, editor and writer, Thomas has traveled from Argentina to Vietnam in pursuit of stories. He holds a Master of Arts in international affairs from American University.