SAM3 - minesweeping Unmanned Surface Vehicle (USV)
Remotely Operated Vehicle (ROV) "are unmanned underwater robots that are controlled by a pilot, via a tether that is spooled out from a support vessel (i.e., either a ship or another underwater vehicle)".
Autonomous Underwater Vehicle (AUV) "are untethered and unmanned submersibles. ..AUVs can be preprogrammed to conduct various measurements, video surveillance, etc. Since they are independent of the surface, they are typically battery powered and controlled by computers using various levels of artificial intelligence."