The Atlantic Sun (Master William B. Longtin) had developed engine trouble and straggled from convoy ON-165. At 10.00 hours on 15 February 1943 the tanker tried to catch up with convoy when struck by two torpedoes from U-607 on the port side about 150 miles off Cape Race. The first torpedo split the ship in half abaft the midships house and the other blew a large hole in the bow. The forward section sank in 20 minutes. The after section appeared sound enough to be taken into port under power. After the ship broke in two, 22 men led by the chief officer abandoned the after section. They returned two hours later and re-boarded the after part of the ship, going below to change clothing. 30 minutes later, with the men still below, a third torpedo from U-607 struck near the stern post, causing the stern to sink 30 minutes later.

After the hit a lifeboat with eight men cleared the ship half-swamped and without oars. Others went over the side into the sea just before the ship turned over keel up and sank. The ordinary seaman William Golobich was taken prisoner by the U-boat, landed at St. Nazaire on 9 March and eventually taken to the POW camp Marlag und Milag Nord. Those who remained behind faced moderate seas and 25° weather. None of the ten officers, 36 crewmen, 20 armed guards (the tanker was armed with one 5in, one 3in and eight 20mm guns) and one passenger on board survived, except the man who had been taken prisoner.