AUV stands for Autonomous Underwater Vehicle but that doesn’t make it any easier to understand….
There are lots of different sizes and shapes but mostly are small submarines and can be anywhere from 30cm to 3m long weighing up to about 2 Tonnes for the big ones. So the “Autonomous” is because it doesn’t have people inside, it is programmed by a person on a computer using a very high level code or set of instructions. Once the vehicle is put in the water, it swims away and goes below the surface hence the “underwater” bit. When they are underwater mostly at sea they can do a whole range of things, inspecting underwater pipes for the Oil Industry, collecting environmental data such as sea currents and temperature for the Environment agency , better mapping the sea floor for charts or even going out to find ship wrecks.