Freediving, free-diving, free diving, breath-hold diving, or skin diving, is a mode of underwater diving that relies on breath-holding until resurfacing rather than the use of breathing apparatus such as scuba gear.
A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.
Cave rescue is a highly specialized field of wilderness rescue in which injured, trapped or lost cave explorers are medically treated and extracted from various cave environments.
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.
The Cave Diving Group (CDG) is a United Kingdom-based diver training organisation specialising in cave diving.
A clearance diver was originally a specialist naval diver who used explosives underwater to remove obstructions to make harbours and shipping channels safe to navigate, but the term "clearance diver" was later used to include other naval underwater work. Units of clearance divers were first formed during and after World War II to clear ports and harbours in the Mediterranean and Northern Europe of unexploded ordnance and shipwrecks and booby traps laid by the Germans.
Vortex Spring is a commercially operated recreation, camping and dive park located near Ponce de Leon, Florida. It is the largest diving facility in the state of Florida.
Recreational caving in the United Kingdom dates back to the mid-19th century. The four major caving areas of the United Kingdom are North Yorkshire, South Wales, Derbyshire, and the Mendips. Minor areas include Devon, North Wales, and the Scottish Highlands.
The Blue Hole of Santa Rosa, or simply the Blue Hole, is a circular, bell-shaped pool or small lake located along Route 66 east of Santa Rosa, New Mexico that is a tourist attraction and swimming venue, and one of the most popular dive destinations in the US for scuba diving and training. The Blue Hole is an artesian well and cenote that was once used as a fish hatchery.
On August 20, 2010, Ben McDaniel, of Memphis, Tennessee, United States, was reported missing after employees in the dive shop at Vortex Spring, north of Ponce de Leon, Florida, noticed that his pickup truck had remained in the shop's parking lot for the previous two days. McDaniel, who had been diving regularly at the spring while living in his parents' nearby beach house, had last been seen by two of those employees on the evening of August 18, on a dive entering a cave 58 feet (18 m) below the water's surface. While he was initially believed to have drowned on that dive, and his parents still strongly believe his body is in an inaccessible reach of the extensive cave system, no trace of him has ever been found. The state of Florida issued his family a death certificate in 2013.
Pluragrotta is a cave in Rana, Norway. It is the deepest cave in Northern Europe. Most caves in Rana, of which there are some 200, are not suitable for diving.
The history of scuba diving is closely linked with the history of the equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
The following outline is provided as an overview of and topical guide to underwater diving:
The following index is provided as an overview of and topical guide to underwater diving:
In June and July 2018, a junior association football team was rescued from Tham Luang Nang Non, a cave system in Chiang Rai province, northern Thailand. Twelve members of the team, aged 11 to 16, and their 25-year-old assistant coach entered the cave on 23 June after a practice session. Shortly after they entered, heavy rainfall began and partially flooded the cave system, blocking their way out and trapping them deep within.
John Paul Volanthen, is a British cave diver who undertakes cave rescues through the Cave Rescue Organisation, South and Mid Wales Cave Rescue, and the British Caving Association. In 2018, he played a leading role in the Tham Luang cave rescue. He cave-dives as a hobby and conducts rescues as a volunteer. He works as an IT consultant in Bristol.
Richard William Stanton, is a British civilian cave diver who specialises in rescues through the Cave Rescue Organisation and the British Cave Rescue Council. He has been called "one of the world's most accomplished cave-divers", "the face of British cave diving," and "the best cave diver in Europe". Stanton has lived in Coventry for many years, and was formerly a firefighter with the West Midlands Fire Service for 25 years prior to his retirement. In 2018 he played a leading role in the Tham Luang cave rescue and was awarded the George Medal in the Civilian Gallantry List.
The 1973 Mount Gambier cave diving accident was a scuba diving incident on 28 May 1973 at a flooded sinkhole known as "The Shaft" near Mount Gambier in South Australia. The incident claimed the lives of four recreational scuba divers: siblings Stephen and Christine M. Millott, Gordon G. Roberts, and John H. Bockerman. The four divers explored beyond their own planned limits, without the use of a guideline, and subsequently became lost, eventually exhausting their breathing air and drowning, with their bodies all recovered over the next year. To date, they are the only known fatalities at the site. Four other divers from the same group survived.
Cave diving is underwater diving in water-filled caves. The equipment used varies depending on the circumstances, and ranges from breath hold to surface supplied, but almost all cave diving is done using scuba equipment, often in specialised configurations with redundancies such as sidemount or backmounted twinset. Recreational cave diving is generally considered to be a type of technical diving due to the lack of a free surface during large parts of the dive, and often involves planned decompression stops. A distinction is made by recreational diver training agencies between cave diving and cavern diving, where cavern diving is deemed to be diving in those parts of a cave where the exit to open water can be seen by natural light. An arbitrary distance limit to the open water surface may also be specified. Despite the risks, water-filled caves attract scuba divers, cavers, and speleologists due to their often unexplored nature, and present divers with a technical diving challenge.
