Snorkels

A snorkel is a tube about thirty centimeters (twelve inches) long, usually J-shaped, fitted with a mouthpiece, and constructed of rubber or plastic. It is used for breathing air from above the water surface when the mouth and nose are submerged, either when snorkeling or during a surface swim before or after scuba diving. The snorkel usually has a piece of rubber that attaches the snorkel to the outside of the strap of the diving mask, as sticking the snorkel in between the strap and the mask could cause the mask to leak, or risk losing the snorkel should the diver choose to switch to scuba.

The most common type of snorkel is a simple tube that is allowed to flood when underwater. The snorkeller expels water from the snorkel either with a sharp exhalation on return to the surface or by tilting the head backwards once the head is above water.

Some modern snorkels have a sump in the mouthpiece to allow a small volume of water to remain in the snorkel without being inhaled when the diver breathes. Some also have a one-way output valve in the sump, which automatically drains the sump as it fills with water. Some dry snorkels have float-operated valves attached to the surface end of the tube to keep water out when the snorkeller submerges.