The ARA San Luis is a Type 290 diesel-powered submarine of the Argentine Navy. Built in Germany as one of a batch of four, San Luis has a displacement of 1,285 tonnes and was introduced to the ARA in 1978.

San Luis is most famous for serving in the Falklands War from March to June 1982. Only one other submarine, the ARA Santa Fe was operational at this time. After the Santa Fe was captured by the British in South Georgia on April 28, and the nuclear submarine HMS Conqueror had sunk the ARA General Belgrano on May 2, the Argentine fleet retired to port for the duration of the war, with the exception of the San Luis, making her the only Argentine naval presence facing the British fleet. The presence of the San Luis was worrying for the British as she was relatively modern and difficult to detect.

San Luis reported two attacks on Royal Navy ships during the war. On May 1, the RN ships HMS Brilliant and Yarmouth were sent to intercept the San Luis in the Falkland Sound channel. San Luis reported firing two torpedos at the ship which subsequently missed.

San Luis attacked again on the night of May 10. Alacrity had made passage up the Falkland Sound, sinking an Argentine merchant navy ship on the way. As Alacrity left the channel before dawn, its sister ship Arrow was waiting to escort her back to the Task Force. San Luis detected the two ships and fired upon them, again missing.

For the rest of the war, San Luis tracked the British ships, but with no successful attacks.