Limbo, or Anti Submarine Mortar Mark 10 (A/S Mk.10), was the final development of the forward-throwing anti-submarine weapon Squid, designed during the Second World War[1] and was developed by the Admiralty Underwater Weapons Establishment in the 1950s.

Limbo was widely employed by the Royal Canadian Navy, being incorporated into all destroyer designs from the late 1950s to the early 1970s, including the St. Laurent, Restigouche, Mackenzie, Annapolis and Iroquois classes and the Type 12 President Class frigates built for the South African Navy in the 1960s.

Limbo was loaded and fired automatically with the crew under cover and was stabilised in pitch and roll.

The weapon was linked to the sonar system of the ship, firing on command when the target was in range.

The rounds were projected so that they fell in a triangular pattern around the target in any direction around the ship.