A snorkel is a device used for breathing air from above the surface when the wearer's head is facing downwards in the water with the mouth and nose submerged. It may be either separate or integrated into a swimming or diving mask. Snorkels come in many colors and options. Snorkels may be open, semi-dry, or dry.
An open snorkel will allow water to flow into the snorkel with ease, a semi-dry snorkel has vents to block water from entering due to a splash or wave and a dry snorkel will seal off in the event of submersion and not allow any water to enter the tube.