Cave and technical diving: a history.

This page is history. The accident analyses described here are told as published work by named authors in named years; they are not instructions, and nothing here describes how to dive in a cave or beyond recreational limits. That takes specialist training, covered in outline on specialty certifications.

Britain: the Cave Diving Group

According to Wikipedia, Graham Balcombe and Jack Sheppard pioneered cave diving in the late 1930s, mainly at Wookey Hole in Somerset. Divernet (1 April 2024) describes a dive there on 18 August 1935, led by Balcombe with Penelope Powell as Diver No. 2, as the first successful cave dive using breathing equipment in Britain; a 2017 PADI blog gives the date as 14 July 1935, and the two may be different dives. Powell's story is on women in diving.

The Cave Diving Group (CDG) was formed in 1946. Its own history page says three Bristol University students formed a separate Independent Cave Diving Group the same year, which joined the CDG in 1965. The CDG describes itself as the oldest amateur technical and cave diving organisation in the world, and Wikipedia calls it the world's oldest continuing diving club. Its founding credit is given three ways:

• Wikipedia names Balcombe as the founder.
• The CDG's own page on Balcombe, seen as a search summary, says he co-founded it.
• An Advanced Diver Magazine article, also seen as a search summary, says Balcombe and Sheppard recruited cavers at Ogof Ffynnon Ddu in South Wales at Easter 1946.

The CDG's history records Mike Boon passing Sump Six in Swildon's Hole using air cylinders in 1961, which it lists among the firsts of that period. It says Jochen Hasenmayer set a European sump penetration record at Keld Head in 1978, and that the group published Geoff Yeadon's "Line Laying and Following" in 1981.

The United States: the NSS Cave Diving Section

The NSS Cave Diving Section's history page records John Harper and Joe Fuller setting a 1,000-foot cave penetration record at Hornsby Sink in 1962. It says the Section was founded in 1973 by cave-diving members of the National Speleological Society, out of meetings at the NSS conventions in Missouri and Indiana, with Sheck Exley as its first chairman. Wikipedia dates Exley's start as chairman to 6 February 1974.

The Section's history says cave-diving deaths peaked at 26 in 1974. That is the Section's own figure. It goes on to list its first instructor institute, in Branford, Florida, in 1980, the NSS Cave Diving Manual in 1982 and the NSS Cavern Diving Manual in 1988.

Sheck Exley

Wikipedia gives Exley's birth as 1 April 1949 and says he began diving and entered his first cave in 1965, at 16. A eulogy by Rodger Ling and Wikipedia both say he was the first person to log more than 1,000 cave dives, and that he made more than 4,000 over more than 29 years. Wikipedia says he co-wrote "Mapping Underwater Caves" with Bob Friedman in 1973 and spent eight days in the Hydrolab habitat in the Bahamas that spring.

His deep dives at Rio Mante in Mexico are recorded differently. Ling's eulogy gives 881 feet on trimix in March 1989. Another source, seen as a search summary, gives 267 m (about 876 feet) on 28 March 1989, after 237 m on 5 April 1988. Ling's eulogy also says Exley set a penetration record of more than two underwater miles at Cathedral Canyon, Florida, in 1990, and reached 863 feet at Bushmansgat in South Africa in August 1993; we found no second source for those two.

Exley died on 6 April 1994 at Zacaton, in Tamaulipas, Mexico, aged 45, during an attempt to go beyond 1,000 feet, on the same day that Jim Bowden reached a record depth there. The maximum depth recorded on his computer is reported as 879 feet in Ling's eulogy and as 906 feet (276 m) in Wikipedia's article on Exley. Wikipedia's article on Zacaton gives a range of 268 to 276 m and attributes the death probably to high-pressure nervous syndrome.

Exley's accident analysis

Exley also studied how cave divers died. The NSS Cave Diving Section says his "Basic Cave Diving: A Blueprint for Survival" was published by the Section in 1979 and was based on accident analysis. Wikipedia describes it as 46 pages in ten chapters, each opening with a real accident (with names changed) followed by an analysis of which accepted practices had been broken. A Goodreads listing dates it to 1 June 1986, which Wikipedia's Exley article identifies as the fifth edition.

An InDEPTH article by Stratis Kas (30 April 2025), reproducing text from GUE's book "Deep Into Cave Diving", says Exley grouped the cave-diving deaths he studied under three causes: the absence of a continuous guideline to the exit, an inadequate reserve of gas, and excessive depth. It says inadequate training and inadequate lighting were added as contributing causes in 1984, giving what became known as the "five rules of accident analysis", which the article says remain central to training for overhead environments. The NSS Cave Diving Section also credits Exley with proposing the "Rule of Thirds" for gas management in 1968, and the CDG's history credits the "Thirds Rule" to him as well. Both are named here only as part of the record.

The same 2025 InDEPTH article also argues the analysis has limits: that Exley did not account for contributing factors, that his categories are far from complete, that rebreathers and scooters came after it, and that risk factors are no longer tracked with statistical precision. That is the author's view as of 2025.

Wakulla Springs, 1987

In an aquaCORPS interview by Michael Menduno (January 1994, later republished by TDI), Bill Stone says the Wakulla Springs Project in Florida was funded in December 1986 and began in October 1987, with more than 450 dives at 260 to 320 feet. The interview credits the project with pioneering open-circuit mixed-gas diving, long-range scooters, a variable-depth decompression habitat called the "microbell", and Stone's first rebreather, the Mark-1, which was tested on a 24-hour dive. How much passage the team explored is given two ways: the interview says more than 2.3 miles, while Wikipedia says the team penetrated 4,160 feet (1,270 m) from the entrance. A search summary of Wikipedia says Exley, Wes Skiles and Paul Heinerth were on the team and that Skiles filmed it for National Geographic.

Naming technical diving

Michael Menduno says he founded the magazine aquaCORPS in January 1990 and first used the term "technical diving", borrowed from technical climbing, in its third issue in January 1991. He says an editorial by Drew Richardson in PADI's Undersea Journal later that year helped make the term respectable. This is the coiner's own account. Menduno also says aquaCORPS held the first annual technical diving conference, Tek.93, in Orlando in January 1993, which led to a set of "Blueprint for Survival 2.0" recommendations in June 1993.

Wikipedia notes that experts still disagree on exactly what counts as technical diving. The agencies that formed around it in the 1990s, including IANTD, TDI and GUE, are on how the agencies began, and the parallel fight over nitrox is on nitrox comes to recreational diving.