While patrolling in the Malacca Strait on August 2, 1942 the submarine HNLMS O-23 spotted a five ship convoy northwest of Penang, taking up a firing position at least one torpedo slammed into the Japanese freighter Zenyo Maru. The ship caught fire and was abandoned by most of her crew, twenty-seven however failed to get off the ship and perished due to the initial explosion or the resulting fires. Fortunately for the crew of O-23 the escorting ship was too far out of position to effect a counterattack and they slipped away to fight another day. The wreck of Zenyo Maru was later towed to singapore and scrapped.