Nereus: Robot Explorer of Challenger Deep

"Robot sub reaches the world's deepest abyss"
New Scientist (June 2, 2009)

"A robotic submarine named Nereus has become the third craft in history to reach the deepest part of the world's oceans, at the bottom of the Mariana Trench in the western Pacific Ocean.

"The dive to Challenger Deep, an abyss within the Mariana Trench that reaches 11,000 metres beneath the waves, was completed on 31 May by a team from the Woods Hole Oceanographic Institution (WHOI), Massachussetts, US...."

Nereus is the third vehicle to intentionally visit the Challenger Deep, a particularly deep part of the Mariana Trench. The first was the U. S. bathyscaphe Trieste in 1960, the second was the Japanese robot Kaiko, in 1995.

That photo is the only one released so far from the Nereus descent. It shows part of the robot submersible, at the bottom of Challenger Deep.

Quite a lot has happened since Kaiko was designed. One feature of Nereus that its makers discuss is its tether-free operation. Without a cable running up to the surface - a matter of miles - Nereus has much greater mobility, they say.