It can operate as an autonomous, free-swimming vehicle to fly on pre-programmed missions over wide areas, mapping the seafloor, gathering data on the oceans, and searching for specific research targets. But then engineers can convert it within a few hours into a tethered vehicle connected via a hair-thin, 25-mile long cable, which enables scientists on the surface ship to receive real-time video images and send instant commands to maneuver the vehicle and its mechanical arm for close-up investigations and sample gathering. Nereus can also work in the deepest parts of the ocean, from 6,500 meters to 11,000 meters (21,500 feet to 36,000 feet), a depth currently unreachable for routine ocean research. After more testing and development, the goal is to aim Nereus to explore the deepest known waters on the planet-Challenger Deep, a trench in the Pacific Ocean southwest of Guam. The trench is deeper than Mount Everest is high, extending almost 11,000 meters (36,000 feet) beneath the sea surface.
Photo by Tim Shank, Woods Hole Oceanographic Institution