From the patrol report of USS HOE (SS-258) on 24 February 1945 at 1700: “While at 60 foot, speed 1.8 kts, course north, Lat. 13-30.9 N, Long. 109-29.1 E. struck what I thought to be a rock. Ship took a four degree up angle and broached. Went to battle stations and blew all main ballast tanks. …On the way to the conning tower one look in the forward torpedo room showed that we had not holed the pressure hull. (The shock felt to me as though we had grounded forward on the starboard side.)” At 1711, having sighted a ship and an airplane, HOE submerged.
From the patrol report of USS FLOUNDER (SS-251) on 24 February 1945 at 1700: “All clear on sound, all clear by periscope, depth 65 feet. Suddenly the whole ship gave a peculiar shudder. Started deep. 30 seconds later ship gave another shake and water started entering boat through the APR cable. Shear valve was closed and stopped leak. Sound soon reported a tremendous rush of air and high speed screws, starting and stopping on our starboard bow. By this time we had figured out that someone has run into us. Screws began to get fainter so at [1711, or 5:11 PM] came to periscope depth and took a look. Calm seas, blue skies, nothing in sight. We were then convinced we had run into a Jap sub and we hoped that he had sunk.”
In actuality, it was later determined, FLOUNDER and HOE had run into each other in one of the only underwater collisions ever reported. Had FLOUNDER surfaced just a moment sooner, she might have seen HOE and the mystery could have been solved on the spot. Instead, HOE steamed away thinking she’d tangled with a small piece of the bottom of the ocean, and FLOUNDER left hoping she’d aided the war effort by destroying an enemy vessel.