Sheck Exley

Sheck Exley (April 1, 1949 – April 6, 1994) was an American cave diver. He is widely regarded as one of the pioneers of cave diving, and he wrote two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man. On February 6, 1974, Exley became the first chairman of the Cave Diving Section of the American National Speleological Society. During his career, he established many of the basic safety procedures used in cave and overhead diving today.

For purposes of rescue during cave diving, Exley helped standardize the usage of the "octopus", a redundant second stage diving regulator that can be used as a backup in the event the diver's primary second stage fails, or alternatively, to allow the diver and their buddy to have simultaneous access to the diver's gas if the buddy has an out-of-gas emergency.

In the book, Diving into Darkness (a story about Dave Shaw and Don Shirley), the author comments: "Exley's status in the sport is almost impossible to overstate".

Early life and career outside of diving Exley began diving in 1965 at the age of 16. That same year he entered his first cave and was hooked on cave diving for the rest of his life. To finance this passion, Exley worked as a mathematics teacher at Suwannee High School in Live Oak, Florida.

In spring 1973, Exley served as an aquanaut during an eight-day mission aboard the Hydrolab underwater habitat in the Bahamas.

Records Exley was the first man in the world to log over 1,000 cave dives (at the age of 23); in 29 years of cave diving, he made over 4000 dives.

Exley was the first person in the history of technical SCUBA diving to dive below . His carefully planned multistage decompressions from these dives, in open water (not in a decompression tank), sometimes required times of as much as 13.5 hours. However, he never suffered a classic case of decompression sickness in his career.

Death Exley died, aged 45, on April 6, 1994, while attempting to descend to a depth of over in a freshwater cenote, or sinkhole, called Zacatón in the state of Tamaulipas, Mexico. He made the dive as part of a dual dive with Jim Bowden, but Bowden aborted his descent early when his gas supply ran low. Exley's body was recovered when his support crew hauled up his unused decompression tanks. It was found that he had looped into the descent line, perhaps to sort out gas issues.

The cause of Exley's death could not be determined. Team members concluded the causes "...could include stress of HPNS exacerbated by the narcotic effects of nitrogen at that depth". The line was also wrapped (deliberately) around Exley's tank valves. Bowden and other experts have theorized that Exley might have done this in anticipation of his own death to prevent any dangerous body recovery operations.

The Sheck Exley Award is given by the National Speleological Society - Cave Diving Section for 1000 safe cave dives post full cave training.

Books , coauthored with Bob Friedman