Another overhaul followed, and on 7 June she left of Moreton Bay on a course for the Solomon Islands. Within the week, she was on patrol off Guadalcanal, operating from there to Savo and Florida Island. A few days later, she shifted south of Guadalcanal and on 21 June sank the converted gunboat "Keijo Maru". At 14:15, "S-44" fired her torpedoes. Just three minutes later the enemy aircraft dropped a bomb which exploded close to the submarine, bending the holding latch to the conning tower and allowing in 30 gallons of sea water. This damaged the depth gauges, the gyrocompass, and the ice machine, besides causing leaks. The number-one periscope was thought to be damaged; but when the submarine surfaced a Japanese seaman's coat was found wrapped around its head.