Royal Navy motor launches attack a submerged German U-Boat (submarine) after detecting it through a hydrophone, a type of underwater microphone.

These motor launches have likely dropped depth charges in the hope of hitting the submerged U-Boat, and are searching the area for debris while listening for further sounds of the enemy. Motor launches helped counter the U-Boat threat, carrying out duties that included patrolling anti-submarine barriers like minefields and underwater steel nets.

George Metcalf Archival Collection
CWM 20030213-002_31