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Saturday 25 October 2014

Diving

The use of diving bells is recorded by the Greek philosopher Aristotle in the 4th century BC.

Diving daredevil Jacques Mayol became the first man to reach a depth of 100 m (330 ft) undersea without breathing equipment on November 23, 1976.  He followed up the record in 1983 with a free dive to 105 metres (346 ft) at the age of 56. Mayol's life formed the basis of Luc Besson's 1988 film The Big Blue, which he co-wrote.

Mayol's Italian friend and rival Umberto Pelizzari later beat his record with a free dive of 131 metres (432 ft).

Director James Cameron pitched the motion picture Titanic to the film studios so that they would fund his diving expedition; not because he wanted to make the movie.

On March 26, 2012, Cameron reached the bottom of the Mariana Trench, the deepest part of the ocean, in the Deepsea Challenger submersible. He was the first person to do this in a solo descent, and is only the third person to do so ever. The data Cameron collected resulted in interesting new finds in the field of marine biology, including new species of sea cucumber and squid worm.

Herbert Nitsch is the world record holder for the deepest no-limit male freedive. On June 6, 2012 he dived to a depth of 253 metres (830 ft) in Santorini, Greece. After the dive he suffered severe decompression sickness.


Egyptian scuba diver Ahmed Gabr set a new record on September 18-19, 2014 for the deepest salt water scuba dive, at 332.35 meters (1,090 feet 4.5 inches). The 14-hour feat took Gabr down into the abyss near the Egyptian town of Dahab in the Red Sea, where he works as a diving instructor.

Gabr is a highly experienced technical diver who trained for four years before attempting the record-breaking dive. He used a special blend of breathing gas called trimix, which contains a mixture of oxygen, nitrogen, and helium. This type of gas is necessary for deep dives because it prevents the diver from experiencing nitrogen narcosis, a state of intoxication caused by the build-up of nitrogen in the bloodstream at high pressure.

The Bajau peoples of South East Asia are the first known humans that are genetically adapted to dive. Their bodies are genetically modified for diving, so much so that they can dive at around 200 ft deep for as long as 13 minutes.

Scuba stands for Self-Contained Underwater Breathing Apparatus.

By Soljaguar - Own work, Wikipedia

Nitrogen narcosis, a shift in consciousness experienced by deep divers in high-pressure water, produces a state similar to drunkenness. After descending 50–70 meters (165–230 feet), divers have reported sleepiness, confusion, and hallucinations.

The bezel on a dive watch only turns counterclockwise so that if the bezel is bumped accidentally during a dive it will only move in one direction, subtracting time from the dive and prompting the diver to surface early rather than staying under for too long.

The actor Jason Statham almost drowned during the filming of The Expendables 3 when a truck's brakes failed and it plunged into the Black Sea. He survived thanks to being an Olympic-class diver.

When free divers dive to depths of several meters, their body undergoes a number of physiological changes in order to conserve oxygen. One of the most notable changes is a decrease in heart rate, which can drop as low as 11 beats per minute. This is known as bradycardia. This biological adaptation allows the diver to conserve oxygen in the blood and prolong the time they can remain underwater. The heart rate of diving for seals, whales and dolphins also drop significantly as a mechanism to preserve blood-oxygen levels.

Divers working on deep-sea infrastructure such as oil pipelines live in a pressurized chamber for a month, taken between the chamber and their work-site by a pressurized diving bell. That way, they only need to be decompressed once, at the end of each 28-day job.

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