Unmanned surface vehicles (USVs), also known as unmanned surface vessels, autonomous surface vehicles (ASVs), or, in some situations, uncrewed surface vessels (USVs), are boats or ships that operate on the water’s surface without a crew. USVs have varying degrees of autonomy, ranging from remote control to totally autonomous. Unmanned underwater vehicles (UUVs), sometimes known as underwater drones, are submersible vehicles that can operate without a human occupant underwater.