Sheck Exley

Sheck Exley (April 1, 1949 – April 6, 1994) was a cave-diving and open-circuit scuba diving pioneer. He is widely regarded as one of the pioneers of cave diving, writing two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man. During his career he establishing many of the basic safety procedures used in cave and overhead diving today. Exley was also a pioneer of extreme deep scuba diving.

For purposes of rescue during cave diving, Exley co-invented the "octopus," or second stage diving regulator with multiple low-pressure-hoses (including one for drysuit or buoyancy device inflation) and another for a redundant backup mouthpiece. This type of second stage regulator is now standard in the sport.

To finance this passion, he worked as a mathematics teacher at Suwannee High School in Live Oak, Florida.

He died at age 45 while trying to set a depth record in a fresh water cenote more than 1000 feet deep, in Mexico.

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."