Basic theories in dive science for beginners
A simple explanation of Boyle’s, Henry’s, and Dalton’s laws that govern the physics of diving and explain what happens to your body.
Understanding the basic physical laws makes you a safer diver with a deeper understanding of what happens underwater.
Boyle’s law
The basic principle
The volume of a gas is inversely proportional to pressure. In other words, the more the pressure increases, the more the gas is compressed to a smaller volume.
Its application in diving
Air in your lungs compresses with depth, which explains why the lungs compress in freediving. It also explains why air expands on ascent and must be released slowly in cylinder diving.
Henry’s law
The basic principle
The amount of gas dissolved in a liquid is proportional to its pressure. The more the pressure increases, the more gas dissolves in the blood and tissues.
Its application in diving
At depth, more nitrogen dissolves in your tissues. On a correct ascent it leaves slowly through breathing. On a rapid ascent it forms bubbles that cause decompression sickness.
Dalton’s law
The basic principle
The total pressure of a gas mixture equals the sum of the partial pressures of each gas in it.
Its application in diving
At depth, the partial pressure of oxygen and nitrogen rises, which may cause oxygen toxicity or nitrogen narcosis at greater depths.
These laws are not just theories. They are the scientific explanation of everything that happens to you underwater.