Scuba diving equipment comes in various shapes and sizes, with the most notable being the Self-Contained Underwater Breathing Apparatus (SCUBA) divided into open and closed circuit equipment. Other gear includes protective suits, fins, flotation devices, and electric propulsion vehicles.
Scuba diving equipment is used by people who want to immerse themselves in water for extended periods of time and comes in many shapes and sizes. The most notable type of diving equipment is the Self-Contained Underwater Breathing Apparatus, or SCUBA equipment, which is divided into two main categories: open circuit and closed circuit equipment. Beyond the snorkel itself, however, there is a wide range of additional scuba equipment that a diver can rely on to make their experience more enjoyable.
Open circuit SCUBA equipment is the simplest type of scuba equipment and is also the most commonly used. It is often referred to simply as scuba and involves the diver inhaling from the equipment and exhaling into the surrounding water. Open circuit equipment was invented by Jacques Cousteau and the modern single tube type was invented by Ted Eldred. The alternative to open loop gear is closed loop gear, often referred to as a rebreather. In a rebreather system, air is inhaled out of the equipment and exhaled back into the equipment, where it is processed so it can be breathed again.
For longer dives, a closed circuit system is often preferable, because longer durations can be achieved with a comparable weight. For example, an average size rebreather tank and a decent soda lime scrubber to filter the air can allow for four to five hour dives. In contrast, an average open circuit system allows for a dive of only about an hour or less, making it suitable for sport diving, but little else.
Other types of scuba gear eschew both open and closed circuit scuba diving entirely. A snorkel, for example, is a very low-tech form of underwater breathing device, essentially consisting of a short tube that allows a shallow diver to keep his mouth and nose underwater while still breathing air from the surface. . A surface-supplied scuba system is similar to a snorkel, except with a much longer tube, which pumps water to the depths to support the diver. Originally this was used for long professional dives but in the modern world it is often used as Snuba® equipment at depths of only 20-30m for leisure travellers.
In addition to breathing equipment, scuba gear also often includes some form of protective gear to protect the body. A wet suit or dry suit is the most commonly seen type, providing protection from the extreme cold often seen in large bodies of water. The wetsuit allows water to penetrate the neoprene layer, creating a water insulating layer that keeps the body warm. Dry suits, on the other hand, are used in extremely cold water, or in warmer water when the diver expects to be underwater for a long time, and actually block the water from entering. Coveralls are often designed to offer protection from stings or abrasion from rocks or coral.
Other pieces of scuba gear include fins, which allow a diver to move more water when moving the hands or feet, flotation devices such as a backplate or buoyancy compensator, and electric propulsion vehicles for divers to help a diver move faster and further. Divers may also wear special diving masks, dive lights or torches, dive knives, weights, or lift bags to help bring things back to the surface.