Snorkelling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swim-fins. In cooler waters, a wetsuit may also be worn. Use of this equipment allows the snorkeller to observe underwater attractions for extended periods of time with relatively little effort.
Snorkelling is a popular recreational activity, particularly at tropical resort and scuba diving locations. The primary appeal is the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving and it appeals to all ages because of how little effort there is, and without the exhaled bubbles of scuba-diving equipment.
Snorkelling is also employed by scuba divers when on the surface, and search and rescue teams may snorkel as part of a water-based search. It is also a means to an end in popular sports such as underwater hockey, underwater ice hockey, underwater rugby and spear-fishing.
A swimmer’s snorkel is a tube typically about 30 centimetres long and with an inside diameter of between 1.5 and 2.5 centimetres, usually L- or J-shaped and fitted with a mouthpiece at the lower end, and constructed of rubber or plastic. It is used for breathing air from above the water surface when the wearer’s mouth and nose are submerged. The snorkel usually has a piece of rubber that attaches the snorkel to the outside of the strap of the diving mask. An older technique is pushing the snorkel between the mask-strap and the head, but this practice increases the chances the mask will leak.
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 (blast clearing) or by tilting the head back shortly before reaching the surface and exhaling until reaching or “breaking” the surface (displacement method) and facing forward again before inhaling the next breath. The displacement method expels water by displacing its presence in the snorkel with air; it is a more advanced technique that takes practice but clears the snorkel with much greater efficiency.
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 snorkeller breathes. Some also have a one-way output valve in the sump, which automatically drains the sump as it fills with water. A few snorkels have float-operated valves attached to the top end of the tube to keep water out when the snorkeller submerges, and more recent designs have a splash deflector on the top end that directs any water that splashes over the open tube to the outside of the tube, thereby keeping the user’s mouth free from water.
Some snorkels used to be made with small “ping pong” balls in a cage mounted to the open end of the tube to prevent water ingress, but these are no longer sold nor recommended to be used since they are considered hazardous to the snorkeller. Similarly,diving masks with a snorkel built into them are considered unsafe and obsolete.
The optimum design length of the snorkel tube is at most 40 centimetres (about 16 inches). A longer tube would not allow breathing when snorkelling deeper, since it would place the lungs in deeper water where the surrounding water pressure is higher. The lungs would then be unable to inflate when the snorkeller 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 hypercapnia, a build up of carbon dioxide in the blood. The greater the volume in the device, the more this problem is exacerbated.
Snorkellers normally wear the same kind of mask as those worn by scuba divers. By creating an airspace, the mask enables the snorkeller to see clearly underwater. All scuba diving masks consist of the lenses also known as a faceplate, a comfortable skirt, which also encloses the nose, and a head strap. There are different styles and shapes. These range from oval shaped models to lower internal volume masks and may be made from different materials; common choices are silicone and rubber.
Although donning a mask and snorkel and swimming in any body of water would technically constitute “snorkelling,” by and large it is generally accepted that a “snorkeller” would don such gear and practice such activity within the vicinity of a reef, wreck, or other submerged objects, either to observe aquatic organisms including fish, algae, etc. or to look at rock formations. Being non-competitive, snorkelling is considered more a leisure activity than a sport.
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 fellow “experienced” snorkeller, 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 divers and snorkellers).
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 snorkelling locations require snorkellers to wear an inflatable vest, similar to a personal flotation device. They are usually bright yellow or orange and have a device that allows users to inflate or deflate the device to adjust their buoyancy. However these devices hinder and prevent a snorkeller from free diving to any depth. Especially in cooler water, a wetsuit of appropriate thickness and coverage may be worn; wetsuits do provide some buoyancy without as much resistance to submersion.
In the tropics, snorkellers (especially those with pale skin) often wear a rash-guard or a shirt and/or board shorts in order to help protect the skin of the back and upper legs against sunburn.