Barotrauma — pressure-related injury

Barotrauma occurs when gas trapped inside your body expands or contracts too quickly. This happens because the surrounding water pressure changes as you move through the water column.

How pressure affects your body

Water pressure increases by 1 bar for every 10 m of depth. You feel this change immediately during a descent. Most divers experience this in their middle ear or sinuses during a descent to 10 m. The air inside these small cavities must match the external water pressure. You must equalize your ears every meter since failing to do so causes tissue damage.

Pressure is a physical force. While you descend, the air volume shrinks because the surrounding pressure increases. If you do not add air to these spaces, your body tissues will compress painfully. I have seen divers struggle at just 5 m if their sinus passages are blocked by a cold.

Why it matters for dive planning

Safety depends on your physical state. You should avoid diving if you have heavy congestion from a sinus infection. A blockage prevents air from moving into the middle ear. This creates a vacuum that can pull on the eardrum.

Pain is a clear warning sign. If you feel any discomfort, stop your descent immediately. I saw a student in Koh Tao in 2019 suffer a ruptured eardrum because he ignored ear pain. He thought he could push through the discomfort until he reached 15 m. This mistake resulted in a canceled trip and a very painful week of recovery.

Common mistakes during ascent

The most dangerous error happens when you go up. It can also affect your lungs if you hold your breath while ascending. As you rise, the pressure decreases and the air inside your lungs expands. If you hold your breath, that expanding air has nowhere to go. This can cause a lung overexpansion injury.

Always ascend slowly so that the air in your lungs can expand safely without causing a lung squeeze. You should aim for a rate of no more than 9 m per minute. Never force an equalization if you feel resistance during your descent. Forcing it often leads to permanent damage to the delicate structures of the ear.

Connections to Boyle’s Law

Barotrauma is a direct result of Boyle’s Law. This law states that volume and pressure have an inverse relationship. When pressure goes up, volume goes down. When pressure goes down, volume goes up.

This concept also explains why your buoyancy changes. You might notice your BCD feels different at 30 m than it does at 5 m. Understanding these physics helps you manage your air spaces more effectively. Use a descent controller or a lift bag if you find depth changes difficult to manage.

Check your sinus pressure before you enter the water.