Into the briny deep - June 02, 2009
For the first time in more than a decade, scientists have penetrated the deepest part of the Pacific Ocean's Mariana Trench.
Nobody's been to the Challenger Deep since 1998, when Japan's Kaiko submersible last visited the bottommost part of the ocean. On Sunday, a remotely operated vehicle called Nereus made it, clocking in at a dive depth of 10,902 meters, or nearly seven miles. 
Nereus is an odd sort of beast called a 'hybrid remotely operated vehicle', or HROV (see earlier Nature feature on its development, subscription required). That means it can either be attached to shipboard scientists by a thin tether, or disconnect and 'fly' itself autonomously through the depths before returning to the surface.
At the Challenger Deep this weekend, researchers from the Woods Hole Oceanographic Institution, which built Nereus, dropped it with a tether from the research vessel Kilo Moana. It spent 10 hours on the bottom, gathering samples and sending back video. What's it look like down there? Flat and mud-colored, apparently (see image).
Nereus is likely to be the only explorer of the briny deep anytime soon. Kaiko was lost at sea in 2003, and no nations are planning a repeat of the record-setting manned dive of the bathyscape Trieste, which took Jacques Piccard and Don Walsh to the bottom in 1960.
WHOI has more images and background here.
Image: WHOI
