Don Walsh, a pioneering U.S. Navy explorer who, along with the scientist Jacques Piccard, broke the record for human deep submergence by descending nearly seven miles to the ocean’s deepest spot, died on Nov. 12 at his home in Myrtle Point, Ore. He was 92.
His son, Kelly, said he died sitting in his favorite chair.
The two men’s historic dive, on Jan. 23, 1960, was cloaked in secrecy in case it failed — which seemed quite possible, given that the towering waves in the Western Pacific had battered or carried away essential gear. While still at the surface, the 60-foot-long Navy submersible Trieste, a bathyscaph designed by Mr. Piccard’s father, lost its surface telephone. A current meter dangled by a few wires. Damaged and beyond use was the tachometer, which was to have registered the vessel’s speed of descent.
It was raining. Lieutenant Walsh, who was 28, and Mr. Piccard clambered into the submersible’s six-foot personnel sphere, soaking wet.
“We decided to put on dry clothing,” Lieutenant Walsh recalled soon afterward. “It was quite an operation: two grown men changing clothes in a space 38 inches square and only 5 feet 8 inches high.”
As detailed in the 1961 book “Seven Miles Down,” by Mr. Piccard and Robert S. Dietz, an explosion rocked the craft as it neared the bottom, shaking its personnel sphere like a small earthquake. Unable to find the problem, the men continued their descent. What beckoned was the Challenger Deep — 6.8 miles down, the lowest point of the Mariana Trench, itself the deepest of the world’s many seabed recesses.
After nearly five hours, the craft landed on the bottom, stirring up silt and ooze and clouding the small porthole. The men nonetheless spotted a flatfish, which instantly answered an old question: Did the sea’s greatest depths harbor life or a bare desert? “We were astounded to find higher marine life-forms down there at all,” Mr. Piccard recalled.
When the aft searchlight came on, Lieutenant Walsh saw what had rocked the craft: the explosive cracking of a plastic window. It posed no immediate threat, but it could bar the men’s exit at the surface and keep them locked in their personnel sphere for several days as the submersible was towed some 200 miles back to Guam, the operations base.
Quickly, the men ended their scientific observations, cut short plans for taking pictures and, after 20 minutes on the bottom, began their ascent.
For the daylong dive, Lieutenant Walsh had packed only 15 chocolate bars, which, given the new uncertainties, the men began to ration.
After a total of nine hours under the waves, two men with chattering teeth were able to emerge from their frigid craft into bright sunshine, blue skies and tropic heat. Out of nowhere, two Navy jets screamed overhead, dipping their wings in salute.
“Navy’s Bathyscaph Dives 7 Miles in Pacific Trench,” read a headline on the front page of The New York Times. The article quoted the Navy as saying that the men had no difficulties. Soon thereafter, at the White House, President Dwight D. Eisenhower awarded Lieutenant Walsh the Legion of Merit.
In January 1961, President John F. Kennedy’s Inauguration Day parade down Pennsylvania Avenue featured the now-famous submersible. “Navy Conquers Inner Space,” read the banner on the support truck.
Don Walsh was born on Nov. 2, 1931, in Berkeley, Calif., to Don and Marta Walsh. His father was a salesman; his mother worked in the administration of Mills College in Oakland.
He grew up in the Bay Area, where he became fascinated by the Navy. “All the battleships and cruisers would be out anchored in the middle of the Bay,” he told an interviewer with the Naval Historical Center (now the Naval History and Heritage Command) in 1995. “They’d have their searchlights on at night. It was quite a show.”
He graduated from Alameda High School in 1949 and from the Naval Academy, with a degree in engineering, in 1954. He became a submariner when poor eyesight kept him from becoming a pilot.
He served on a number of submarines, including as a commander. He earned a Ph.D. in oceanography from Texas A&M University in 1968 and, after retiring from the Navy in 1975 with the rank of captain, founded the Institute for Marine and Coastal Studies at the University of Southern California.
He was a member of many state and federal panels, as well as the boards of private companies, and in 2001 he was elected to the National Academy of Engineering. In 2003, he became an honorary director of the Explorers Club of New York City.
Late in life, Dr. Walsh began to revisit his pioneering dive site. In 2012, at age 80, he advised the filmmaker James Cameron when he became the first person since Dr. Walsh and Mr. Piccard to make a dive into the Challenger Deep. “I feel so fortunate,” Dr. Walsh said at the time. “Dudes my age are mostly sitting in rockers passing around snapshots of grandkids and great-grandkids.”
He also advised the undersea explorer Victor L. Vescovo when he dived into the Challenger Deep in 2019. The next year, Mr. Vescovo once again made the dive; this time, he took Dr. Walsh’s son, Kelly, as a passenger. The two men spent four hours exploring the planet’s deepest spot.
In a recent interview, Mr. Vescovo remembered Dr. Walsh not only as a pioneering explorer but also as a person who stood out for his kindness and integrity.
“Everybody who worked with him always commented on what a wonderful human being he was,” he said. “He had an amazing sense of humor, an incredible amount of expertise and a great caring for people and the world. He was what you hoped all great explorers would be.”
Dr. Walsh married Joan Betzmer in 1962. In addition to his son, she survives him, as do a daughter, Liz Walsh; a brother, Michael; a sister, Nan Merritt; and a grandson.
When Kelly Walsh learned of his father’s death, he was giving a talk on a cruise ship in the Pacific about the history of the Challenger Deep explorations, including his own.
“It was the perfect time and place for such a homage to my dad’s legacy,” he wrote in an email. “People were in tears.”