Tahoe diver discovers missing Japanese mega-submarine off coast of Hawaii

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WAIMANOLO, Hawaii – As a teenager, Terry Kerby SCUBA dived and fished the waters of Lake Tahoe for crawdads, those hard-shelled crustaceans resembling lobsters that have wicked-looking, claw-like hands and five pairs of legs.

“My friends and I would camp out at Meeks Bay, Kings Beach and Zephyr Cove and fish for crawdaddies all day long,” said Kerby, who lived with his family at Bass Lake, a tiny resort community in California’s Sierra National Forest near the south entrance of Yosemite National Park.

But today, Kerby, 64, who studied geology at UNLV and served in the Coast Guard, where he won its Commendation Medal for his nighttime rescue off the Puerto Rican coast of two people trapped beneath their capsized boat, is being heralded for the biggest, most important catch of his lengthy career as a lake and ocean explorer:

His recent discovery of the long-lost Imperial Japanese Navy’s mega-submarine/aircraft carrier “I-400” that during World War II was preparing to attack U.S. military installations in the Panama Canal Zone and disable or destroy the canal itself.

The operations director of the University of Hawaii’s Undersea Research Laboratory, Kerby captained the three-man crew of the lab’s battery-powered, headlight-equipped “Pisces 5” cylindrical submersible that discovered the 400-foot-long submarine lying in a 2,300-foot watery grave approximately five miles off the southwest coast of Oahu.

Kerby’s discovery of the sub actually took place in early August of 2013, he said in an interview at his laboratory at the end of Maki Pier near here, about 15 miles east of Honolulu.

But it took him and his team, which included underwater archaeologists and historians from the National Oceanic and Atmospheric Administration’s maritime heritage division, four months to positively identify the wreckage as that of the I-400.

“The wreckage was heavily mangled, partially collapsed, had sunk at a steep angle, and we initially thought is might be the wreck of the Japanese sub I-23, which had 96 men aboard, that had not been heard from since early 1942,” said Kerby.

But working with original plans and photographs of the I-400 supplied by Japan’s current naval leadership, Kerby and his group were able to determine that the sub was in fact the I-400, and the University of Hawaii announced its discovery four months ago.

Kerby also revealed that the submarine had not been sunk by the U.S. during World War II ... that it had been captured by the U.S. Navy during the war and purposely sunk by torpedoes fired by the submarine USS Trumpetfish (SS-425) on June 4, 1946, 10 months after Japan’s surrender.

“Once our search began, it took us several months to find the sub. The Navy hadn’t kept accurate coordinates as to where the Trumpetfish had sunk the I-400, and although we knew approximately where it was located, we spent countless six-hour shifts in Pisces 5 looking for it,” Kerby said.

“The I-400 was one of Japan’s supersubs, and the U.S. sank it because we didn’t want its technology, especially its advanced sonar and radar equipment, to fall into the hands of the Russians at the war’s end when the Cold War was heating up,” he explained.

“The Russians were our allies during World War II, and according to terms set forth in the Japanese surrender documents, the Russians and our other allies were entitled to share in technological revelations discovered from Japanese ships and aircraft,” he said.

The I-400, the largest submarine ever built until the introduction of nuclear-powered subs in the 1960s, had a range of 37,500 miles and was capable of sailing one-and-a-half times around the world without refueling, a capability that to this day has never been matched by any other diesel-electric submarine, Kerby stated.

Rising from the I-400’s massive deck was a 115-foot-long cylindrical hangar that housed three single-engine M6 “Serain” float planes which could be equipped with bombs or aerial torpedoes.

The aircraft, which could reach a speed of 298 mph and had a range of nearly 650 miles, were folded to fit into the hangar, launched from a deck catapult and recovered from the sea by a deckboard crane. All three planes could be prepared, armed and launched within 15 minutes. The submarine itself carried torpedoes and a long-range deck gun. The Japanese Navy during WW II had another, more frightening potential use for the I-400. This involved sailing the submarine close to Western U.S. coastal waters and sending the three aircraft aloft over large cities such as Seattle, Portland, San Francisco and Los Angles where they would disperse deadly bacterial agents to spread bubonic plague, cholera, typhoid fever and other epidemic diseases.

But these plans were never carried out.

Terry Kerby, whose team has also located the underwater remains of several WW II 80-foot, two-man Japanese mini-subs off the Hawaiian coast, said the discovery of the I-400 not only resolves a decades-old Cold War mystery but was “certainly was the most satisfying of my underwater explorations.”

And, he added, “There’s no doubt in my mind that my career began in the waters of Lake Tahoe where, as a boy, I SCUBA dived and fished for crawdaddies.”


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