Snorkeling (British spelling: snorkelling) is the practice of swimming at the surface of a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swimfins. In cooler waters, a wetsuit may also be worn. Combining these tools allows the snorkeler to observe underwater attractions for extended periods of time with relatively little effort.
It is a popular recreational activity, particularly at tropical resort destinations and at shallow scuba diving locations. Snorkeling is also employed by scuba divers when near the surface, and search and rescue teams may snorkel as part of a water-based search.
The primary attraction of snorkeling is the opportunity to observe underwater life in a natural setting. This may include coral reefs and their denizens, such as fish, cephalopods, starfish, sea urchins, and mollusks. Snorkeling in sandy areas may allow sighting of rays and various flatfish. Other organisms that can be seen while snorkeling include various forms of seaweed, jellyfish, shrimp, sea turtles, various types of sea cactus and occasionally anything else which may be found in the ocean.
Snorkeling requires no special training, only the ability to swim and to breathe through the snorkel. However, for safety reasons, instruction and orientation from a tour guide, dive shop, or equipment rental shop is recommended. Instruction generally covers equipment usage, basic safety, what to look for, and what to look out for, and conservation instructions (fragile organisms such as coral are easily damaged by snorkelers). As with scuba diving, it is always recommended that one not snorkel alone, but rather with a "buddy", a guide, or a tour group.
Some commercial snorkeling locations require snorkelers to wear an inflatable vest, similar to a life jacket. They are bright yellow or orange and have a valve that allows the user to inflate or deflate the device. It is secured in place by two straps, one around the waist and another behind the user and between the legs.
The mask and snorkel are similar to those used in scuba diving, but since they are not subjected to the pressures of deep water, they can be more lightweight and comfortable. Swimfins used in snorkeling are usually longer than those used in diving.
Experienced snorkelers often start to investigate amateur free-diving, which should be preceded by at least some training from a dive instructor or experienced free-diver.
A swimmer's 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.
Typically, the diving mask also serves to prevent breathing through the nose, so that one is forced to breathe through the snorkel. This also provides some negative pressure which helps keep the mask sealed against the face, though attempting to breathe out through the nose can break this seal and/or fog the mask.
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 snorkeler breathes. Some also have a one-way output valve in the sump, which automatically drains the sump as it fills with water. Some snorkels have float-operated valves attached to the surface end of the tube to keep water out when the snorkeller submerges. The more modern and quality snorkels have a one way valve on the top end that forces any water that splashes over the top to slide out of the sides, keeping the user's mouth free from water.
Snorkels used to be sold with ping pong balls at the end of the tube. They are no longer sold or used, as they are considered hazardous to the snorkeler, as is the obsolete snorkel built into the diving mask.
The maximum usable length of the snorkel tube is around forty centimetres (about fifteen inches). A longer tube would place the lungs in deeper water where the surrounding water pressure is higher and the lungs would be unable to inflate when the diver inhales, because the muscles that expand the lungs are not strong enough to operate against the higher pressure. Snorkels also create what is called "dead air space". When the user takes in a fresh breath, some of the previously exhaled air remains in the snorkel and is recycled into the lungs, reducing breathing efficiency and causing CO₂ retention. The greater the volume in the device, the more this problem is magnified.
Snorkeling is possible in almost any body of water, but snorkelers are most likely to be found in locations where there are minimal waves, warm water, and something particularly interesting to see near the surface. Some of the most popular locations are warm, coral-rich seas such as the Caribbean Sea, the Coral Sea and the Red Sea.