OVERVIEW: The Mk67 SLMM Mod 1 is a submarine-launched mobile mine based on a modified Mk37 torpedo, designed for covert mining operations in shallow or constrained waters. It uses pre-programmed guidance to navigate to its target location before settling as a bottom mine.

DETAILS: The Mk67 Submarine-Launched Mobile Mine (SLMM) was introduced in 1985 to provide the U.S. Navy with a means of clandestinely delivering bottom mines into enemy harbors or narrow waterways. It repurposes the Mk37 torpedo body, replacing the warhead with a mine payload and integrating inertial navigation to follow a programmed course after launch. Once it reaches the designated location, it sinks to the seafloor and arms as a static bottom mine. Unlike traditional mines dropped in-place, the SLMM can be launched from safe stand-off ranges, increasing operational security. Its deployment method is similar to that of a torpedo, using standard 21-inch torpedo tubes.

FUNCTION: Launched from a submarine’s torpedo tube, the SLMM transits underwater along a preset path, then stops and rests on the seafloor, arming itself as a bottom influence mine. It is used to deny access to strategic locations without exposing the launch platform.

NOTE:
IOC: 1985
Operators: United States Navy
Platforms: SSN-class attack submarines with 21-inch torpedo tubes (e.g., Los Angeles class)
Conflict used in: Not used in combat as of 2025

SOURCE: U.S. Navy Mine Warfare Manual ; Jane’s Naval Weapon Systems ; Federation of American Scientists (FAS): https://fas.org/man/dod-101/sys/sea/mk67.htm ; Naval Sea Systems Command technical data ; https://www.navy.mil