A pioneering scuba diver who explored the sites of hydrogen bomb blasts has died.
James Stewart taught generations of scientists to dive for the Scripps Institution of Oceanography at UC San Diego.
The San Diego institute says Stewart died Wednesday in Irvine at age 89. Stewart was a longtime breath-hold or free diver when he first took up scuba.
In 1952 he joined Scripps as a volunteer and later became chief diving officer. He helped develop diving safety procedures and trained thousands of underwater researchers.
Over five decades, Stewart dove all over the world, helped discover underwater sandfalls at Cabo San Lucas and survived a shark attack.
He also consulted for NASA, the FBI, Army Special Forces and National Park Service and developed diver training for the Antarctic, where a mountain is named after him.