Deep diving is underwater diving to a depth beyond the norm accepted by the associated community. In some cases this is a prescribed limit established by an authority, while in others it is associated with a level of certification or training, and it may vary depending on whether the diving is recreational, technical or commercial. Nitrogen narcosis becomes a hazard below 30 metres (98 ft) and hypoxic breathing gas is required below 60 metres (200 ft) to lessen the risk of oxygen toxicity.
An underwater environment is a environment of, and immersed in, liquid water in a natural or artificial feature, such as an ocean, sea, lake, pond, reservoir, river, canal, or aquifer. Some characteristics of the underwater environment are universal, but many depend on the local situation.
Saturation diving is diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas used. It is a diving mode that reduces the number of decompressions divers working at great depths must undergo by only decompressing divers once at the end of the diving operation, which may last days to weeks, having them remain under pressure for the whole period. A diver breathing pressurized gas accumulates dissolved inert gas used in the breathing mixture to dilute the oxygen to a non-toxic level in the tissues, which can cause decompression sickness if permitted to come out of solution within the body tissues; hence, returning to the surface safely requires lengthy decompression so that the inert gases can be eliminated via the lungs. Once the dissolved gases in a diver's tissues reach the saturation point, however, decompression time does not increase with further exposure, as no more inert gas is accumulated.
A submersible is an underwater vehicle which needs to be transported and supported by a larger watercraft or platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent operation at sea.
The equivalent air depth (EAD) is a way of approximating the decompression requirements of breathing gas mixtures that contain nitrogen and oxygen in different proportions to those in air, known as nitrox.
An atmospheric diving suit (ADS) is a small one-person articulated submersible which resembles a suit of armour, with elaborate pressure joints to allow articulation while maintaining an internal pressure of one atmosphere. An ADS can enable diving at depths of up to 700 metres (2,300 ft) for many hours by eliminating the majority of significant physiological dangers associated with deep diving. The occupant of an ADS does not need to decompress, and there is no need for special breathing gas mixtures, so there is little danger of decompression sickness or nitrogen narcosis when the ADS is functioning properly. An ADS can permit less skilled swimmers to complete deep dives, albeit at the expense of dexterity.
SEALAB I, II, and III were experimental underwater habitats developed by the United States Navy in the 1960s to prove the viability of saturation diving and humans living in isolation for extended periods of time. The knowledge gained from the SEALAB expeditions helped advance the science of deep sea diving and rescue, and contributed to the understanding of the psychological and physiological strains humans can endure.
A diving chamber is a vessel for human occupation, which may have an entrance that can be sealed to hold an internal pressure significantly higher than ambient pressure, a pressurised gas system to control the internal pressure, and a supply of breathing gas for the occupants.
A United States Navy diver refers to a service personnel that may be a restricted fleet line officer, civil engineer corps (CEC) officer, Medical Corps officer, or an enlisted who is qualified in underwater diving and salvage. Navy divers serve with fleet diving detachments and in research and development. Some of the mission areas of the Navy diver include: marine salvage, harbor clearance, underwater ship husbandry and repair, submarine rescue, saturation diving, experimental diving, underwater construction and welding, as well as serving as technical experts to the Navy SEALs, Marine Corps, and Navy EOD diving commands.
Joseph Salim Peress, was a pioneering British diving engineer, inventor of one of the first truly usable atmospheric diving suits, the Tritonia, and was involved in the construction of the JIM suit.
A diving watch, also commonly referred to as a diver's or dive watch, is a watch designed for underwater diving that features, as a minimum, a water resistance greater than 1.1 MPa (11 atm), the equivalent of 100 m (330 ft). The typical diver's watch will have a water resistance of around 200 to 300 m, though modern technology allows the creation of diving watches that can go much deeper. A true contemporary diver's watch is in accordance with the ISO 6425 standard, which defines test standards and features for watches suitable for diving with underwater breathing apparatus in depths of 100 m (330 ft) or more. Watches conforming to ISO 6425 are marked with the word DIVER'S to distinguish ISO 6425 conformant diving watches from watches that might not be suitable for actual scuba diving.
The Newtsuit is an atmospheric diving suit designed and originally built by Phil Nuytten.
The breathing performance of regulators is a measure of the ability of a breathing gas regulator to meet the demands placed on it at varying ambient pressures and temperatures, and under varying breathing loads, for the range of breathing gases it may be expected to deliver. Performance is an important factor in design and selection of breathing regulators for any application, but particularly for underwater diving, as the range of ambient operating pressures and temperatures, and variety of breathing gases is broader in this application. A diving regulator is a device that reduces the high pressure in a diving cylinder or surface supply hose to the same pressure as the diver's surroundings. It is desirable that breathing from a regulator requires low effort even when supplying large amounts of breathing gas as this is commonly the limiting factor for underwater exertion, and can be critical during diving emergencies. It is also preferable that the gas is delivered smoothly without any sudden changes in resistance while inhaling or exhaling, and that the regulator does not lock up and either fail to supply gas or free-flow. Although these factors may be judged subjectively, it is convenient to have standards by which the many different types and manufactures of regulators may be objectively compared.
Oceaneering International, Inc. is a subsea engineering and applied technology company based in Houston, Texas, U.S. that provides engineered services and hardware to customers who operate in marine, space, and other environments.
The United States Navy Experimental Diving Unit is the primary source of diving and hyperbaric operational guidance for the US Navy. It is located within the Naval Support Activity Panama City in Panama City Beach, Bay County, Florida.
In underwater diving, ascending and descending is done using strict protocols to avoid problems caused by the changes in ambient pressure and the hazards of obstacles near the surface such as collision with vessels. Diver certification and accreditation organisations place importance on these protocols early in their diver training programmes. Ascent and descent are historically the times when divers are injured most often when failing to follow appropriate procedure.
Captain George Foote Bond was a United States Navy physician who was known as a leader in the field of undersea and hyperbaric medicine and the "Father of Saturation Diving".
Underwater breathing apparatus is equipment which allows the user to breathe underwater. The three major categories of ambient pressure underwater breathing apparatus are:
The history of underwater diving starts with freediving as a widespread means of hunting and gathering, both for food and other valuable resources such as pearls and coral. By classical Greek and Roman times commercial applications such as sponge diving and marine salvage were established. Military diving also has a long history, going back at least as far as the Peloponnesian War, with recreational and sporting applications being a recent development. Technological development in ambient pressure diving started with stone weights (skandalopetra) for fast descent. In the 16th and 17th centuries diving bells became functionally useful when a renewable supply of air could be provided to the diver at depth, and progressed to surface-supplied diving helmets—in effect miniature diving bells covering the diver's head and supplied with compressed air by manually operated pumps—which were improved by attaching a waterproof suit to the helmet and in the early 19th century became the standard diving dress.
The metresea water (msw) is a metric unit of pressure used in underwater diving. It is defined as one tenth of a bar.
