Because radio signals don't travel well through water, Trident is, like many unmanned submarines, a tethered vehicle. The robot will ship with a cord that's 82 feet long, but given a longer cord the makers say the body can work at depths of over 300 feet. Trident has a top speed of about 4 mph and can run on battery power for 3 hours. The robot itself is almost 8 inches wide, 16 inches long, and 3 inches thick. The drone has two thrusters in the back, and a third nested in the middle of its body for gentle vertical maneuvering under water. On its face there's an HD camera and LED lights. The basic model costs $1,200, and a fleet of five are bundled at $3,700. Each comes with a buoy that can transmit data between the user and the Trident wirelessly.