When on the surface, the snorkel means that you can breathe outside air if you find yourself swimming face-down, thereby conserving tank air. Snorkel – This is a small, J-shaped, lightweight respiratory tube with a mouthpiece on one end. The air we breathe is a mixture of principal nitrogen 78 percent and a few oxygens 21 p.c. Pressure affects the quantity of nitrogen and oxygen gases that dissolve in your blood and tissues. Once you inhale air, your body consumes