A very small highly maneuverable ROV. U-CAT is a prototype robotic sunken-ship-exploring sea turtle. U-CAT has four independently-driven flippers that allow it to move up and down, forward and backward, and to pivot on the spot. Propellers would let it do those same things, although they'd also churn up much more visibility-limiting silt in the process. U-CAT is autonomous, so it doesn't require a control cable that could get snagged or tangled. It also has an onboard video camera, which records video that can later be used to visually map out the inside of the shipwreck.