Activities The Great Outdoors Squeeze in Scuba Diving Boyle's Law Share PINTEREST Email Print Hoiseung Jung/EyeEm/Getty Images The Great Outdoors Scuba Diving & Snorkeling Gear Skills Safety Hiking Climbing Skiing Snowboarding Surfing Paddling Fishing Sailing Learn More By Natalie Gibb Natalie Gibb owns a dive shop in Mexico and is a PADI-certified open water scuba instructor and TDI-certified full cave diving instructor. our editorial process Natalie Gibb Updated February 22, 2019 A squeeze occurs when the air pressure inside one of a diver's body air spaces is less than the pressure of the surrounding water. This condition can cause discomfort, pain, or even injury. When a diver descends underwater, the pressure of the surrounding water increases with depth, according to Boyle's Law. Recall that the deeper the diver descends, the greater the pressure of the water around him. Because most of a diver's body is filled with water (an incompressible fluid as far as diving is concerned) he will not feel the effects of water in most of his body; a diver's arms and legs feel just the same as they do on the surface. However, a diver may feel the effects of increased water pressure on his body's air spaces. Air in the Body Compresses With Descension As a diver descends, the pressure inside a diver's body air spaces remains the same as it was on the surface, whereas the pressure of the water around him increases. This increase in water pressure upon descent causes the air in a diver's body air spaces to compress. If the diver does not equalize his body air spaces, this pressure difference causes a "squeeze" the sensation that the water is pushing in or squeezing the air space. Some common air spaces in which a squeeze can occur are the ears, the sinuses, a diver's mask, and even his lungs. Thankfully, a squeeze is easy to correct. Equalizing Air Spaces To prevent a squeeze in scuba diving, a diver simply needs to equalize his body air spaces so that the pressure inside his body is equal to the pressure outside his body. During every entry-level scuba diving course, a diver is taught how to equalize his ears (pinch the nostrils gently and breath out through the nose), his mask (exhale into the mask), and his lungs (breathe continuously). When Is a Squeeze Dangerous? A diver should stop descending the moment he feels a squeeze. Failure to do so may cause a pressure related injury or barotrauma. Barotraumas occur in scuba diving when the pressure outside a diver's body is so unequal to the pressure inside a diver's body that it causes damage to the diver's tissues. Barotraumas that may be caused by scuba diving include ear barotraumas, mask squeezes, and pulmonary barotraumas. Thankfully, barotraumas are easy to prevent in scuba diving. The moment a diver feels a squeeze, he should stop the descent, ascend a few feet to reduce the pressure difference between the water and his air spaces, and equalize his air spaces. During scuba diving courses, divers are taught to equalize their air spaces preemptively, before any pressure or squeeze is felt. Doing so makes the chances of experiencing a squeeze underwater low. Careful divers practice slow and controlled descents (it's harder than it sounds!) and equalize their air spaces every few feet to prevent a squeeze and make scuba diving safe and comfortable.