"Nereus helped us explore places we've never seen before and ask questions we never thought to ask," Timothy Shank of the Woods Hole Oceanographic Institution (WHOI), managers of the sub, wrote in a
press release. "It was a one-of-a-kind vehicle that even during its brief life brought us amazing insights into the unexplored deep ocean, addressing some of the most fundamental scientific problems of our time about life on Earth."
The submersible was lost on Saturday, May 10 while working 10 km (6.2 miles) down in an area known as the Kermadec Trench, northeast of New Zealand; at the time it was lost it was exploring the ocean's hadal region. Debris from the Nereus floated to the surface and scientists believe some of the sub imploded under pressure that would have been in the region of 16,000 pounds per square inch.
It was lost while on an expedition on board the research vessel Thomas G. Thompson, a mission to "...carry out the first-ever, systematic study of a deep-ocean trench as part of the NSF-sponsored Hadal Ecosystems Study (HADES) project."
Taken to a depth of 9,900 metres, the Thompson suddenly ceased receiving data from the Nereus and later debris was located. It was designed to go down to about 11,000 metres (36,000 ft.). In May of 2009 while
exploring the Challenger Deep, the deepest point ever surveyed on Earth, the Nereus went down to 10, 902 metres without incident.