Researchers say "tremendous water pressure" was the result of the crash.
A multimillion-dollar unmanned submarine has imploded during the final stages of a 10-kilometre dive into the Pacific Ocean, according to multiple reports
The Nereus submarine was lost on May 10 while diving in the Kermadec Trench, northeast of New Zealand. The US Woods Hole Oceanographic Institute (WHOI), owner and operator of the Nereus, said "tremendous water pressure" as great as 16,000 pounds per square inch was the result of the crash.
Researchers said they lost contact with Nereus seven hours into the nine-hour dive. "We'd just completed collecting a sea cucumber for the respirometer and were getting Nereus ready to head to the underwater elevator,' writes Ken Kostel, the science editor for WHOI. "Then the camera feeds abruptly went dark, and we lost communication with the vehicle."
The remotely-operated Nereus' only connection to the surface was a fibre-optic cable, but it was also programmed to raise itself if necessary.
''We were nearing the time window associated with the first of those back-up releases when one of the ship's crew spotted some white objects in the water,'' Kostel says. ''Then more. The rescue boat went in and three crew members began scouring the surface with nets as more and more white dots appeared. By then we knew. Nereus was gone.''
The Nereus was built in 2008 for $5 million. It has successfully travelled to the deepest point in the ocean, the 11-kilometre Challenger Deep, and the world's deepest known hydrothermal vents along the Cayman Rise in the Caribbean Sea.
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