What was the longest time a submarine was submerged during world war 2?

USS Puffer (SS-268) holds the record for being submerged longer than any American submarine during World War 2. The incident took place on October 9, 1943 during Puffer's first war patrol. While attacking a Japanese tanker, the submarine was counter-attacked by the ship's escort, forcing the submarine deep to evade. The escort, however, did not relent and, joined later by a second escort, prevented Puffer from surfacing for over 37 hours.