Boeing Testing Huge Drone Submarine off Palos Verdes Coast

The Boeing "Echo Voyager" is a 50-ton, 51-foot-long monstrous underwater robot. The unmanned undersea vehicle is now going through several months of trials at sea before setting off on its own with no crew and no tether to a support ship.

Powered by a hybrid electric battery system, it periodically surfaces to snorkel depth to recharge its batteries by raising a mast.

The Echo Voyager can reach an impressive depth of 11,000 feet.

It will be used for months-long surveillance and reconnaissance missions for defense, commercial and scientific customers.