Robotic Nereus submarine aims to explore the depths of Challenger Deep

Robotic submarines have already achieved some pretty impressive feats of submersion, but this new Nereus sub developed by the folks at the Woods Hole Oceanographic Institution looks set to out-do those in a fairly big way, with it now on track to dive down into all 11,000 meters of the Challenger Deep in the Pacific Ocean. What's more, while the sub can be operated remotely, it also has a fully autonomous mode, which'll let it make use of the on-board chemical sensors, sonar, and digital photography to seek out areas of interest and map out "vast swathes of the seafloor" before returning to the ship automatically. As you might have guessed, all of that comes at a fairly hefty price tag -- about $5 million -- and it seems like may only be the first of a flood of robotic submarines to come, with British, French, Russian and Japanese teams said to be watching the Nereus' progress "with interest." It doesn't look like they'll have to wait all that long for the big show, however, as the sub is apparently now starting to undergo a series of progressively difficult test dives in advance of the main event planned for late May or early June.