Tokyo, July 01: The world's deepest-diving submarine has disappeared in the choppy Pacific Ocean off Japan, a setback to deep-sea research on everything from earthquakes to rare bacteria. Kaiko, a bright yellow submarine which entered the record books in 1995 by diving 10,911 meters to the bottom of the challenger deep - the ocean's deepest point - snapped its tether as a typhoon approached in late may and has been missing since then, officials said yesterday.

The Japan marine science and technology center will decide on Thursday whether to continue searching for it, spokesman Tomoaki Kanai said.

"We have no idea why it broke free. This is a first. But if we lose it, it's going to have a big impact on deep-sea research," Kanai said yesterday.

Daniel J Fornari, chief scientist for deep submergence at the woods hole oceanographic institute in Massachusetts, called the disappearance of the 3-meter-long unmanned submersible "an enormous loss" for science.
"It was unique in the world," he said. "There is no doubt that it is going to be sorely missed. ... It's not something that you can go out and buy at your local deep sea equipment store."

Equipped with two robot arms and four television cameras, the USD 15 million Kaiko is the world's only probe that can go deeper than 6.9 kilometers.

Bureau Report