If you come across an unmanned, deep-sea exploration robot called Nereus, the Woods Hole Oceanographic Institution (WHOI) would like to have a word with you: Nereus reportedly went missing this past Saturday in the midst of a dive 6.2 miles into the Kermadec Trench northeast of New Zealand. Given the intense pressure it was under (as much as 16,000 pounds/square inch), scientists presume some of it to have imploded in the deep.

“Nereus helped us explore places we’ve never seen before and ask questions we never thought to ask,” said chief scientist Timothy Shank. “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.”

Nereus was deployed from the research vessel Thomas G. Thompson, and was 30 days into a 40-day mission when it was lost. The team says they officially lost contact with the vessel seven hours into the dive. Though a search near the dive site proved unsuccessful, they did recover debris that they later identified as belonging to Nereus. The debris indicates that Nereus likely suffered a catastrophic implosion.

Nereus was no rookie when it came to deep-sea exploration – earlier, it traveled to Challenger Deep in the Mariana Trench—the deepest point in the ocean—and explored the world’s deepest known hydrothermal vents along the Cayman Rise in the Caribbean Sea. It helped scientists discover previously unknown animal species, and was helping researchers explain heretofore unknown chemical and biological processes in the ocean’s deepest reaches.

“Extreme exploration of this kind is never without risk, and the unfortunate loss of Nereus only underscores the difficulty of working at such immense depths and pressures,” said WHOI Director of Research Larry Madin. “Fortunately there was no human injury as a consequence of this loss. WHOI scientists and engineers will continue to design, construct and operate even more advanced vehicles to explore and understand the most remote and extreme depths of our global ocean.”