Forty two men on board the USS R-12 SS-89 were lost when the submarine sank for unknown reasons on June 12, 1943 off Key West, Florida. Five men, including the commanding officer, were on the bridge and managed to escape. While no definitive answer for the loss was ever given it is thought that an open torpedo door lead to flooding in the forward compartment.

After the collision alarm was sounded the captain was informed of flooding in the forward compartment, he ordered all ballast tanks blown, but the boat sank 15 seconds later. Because this occurred in war time and because the boat was 600 feet down no recovery effort was made and the wreck is still there. Of the 42 who died two were Naval officers from Brazil who were on board to observe torpedo firing exercises. Luckily eleven of her crew were on leave at the time of her loss and thus were spared the fate of the remainder of the crew.