British ship Challenger II bounces sound off the bottom, and near Guam finds what appears to be the sea's deepest chasm, its lowest point nearly seven miles down, subsequently named the Challenger ...

Walsh, who died just over a year ago, was the first person - along with Jacques Piccard - to visit the lowest point on Earth ... Walsh's ship is called T-AGOS 25, Vescovo’s T-AGOS 26.