"Angler" sailed on 3 May for another patrol as one of eight submarines assigned to support the carrier strike scheduled to hit Surabaya, Java. Their job would be to sink retreating Japanese ships, to provide lifeguard services, and to guard the major passages from the Java Sea (the Sunda Strait and Lombok Strait) to the Indian Ocean lest the Japanese try to move into the Indian Ocean to attack the Allied strike force. Launched as scheduled on 17 May the strikes achieved complete surprise.