The submarine launched anti-submarine standoff weapon, Sea Lance, was intended to replace SUBROC, although it was cancelled while in full scale engineering development phase. Sea Lance was to carry the newly developed Mark 50 Advanced Light Weight Torpedo (ALWT) payload and the development program included an option for follow-on, nuclear bomb payload variant. Sea Lance incorporated a digital guidance system similar to the inertial guidance system used in ADCAP.
Sea Lance was capable of deep launch from a submarine torpedo tube with one of the two warhead options. The missile then is buoyed to the surface in a water-tight container where the solid propellent rocket motor ignites and delivers the weapon the target area at supersonic speed. At a point above the suspected target area, the warhead detaches form the rocket and parachutes to the water. Upon contact with water, the torpedo warhead assumes its search and attack pattern.
The deployment of Sea Lance was intended to complement the capabilities of the ADCAP torpedo by providing a stand-off option whereby an enemy submarine can be incapacitated from a distance well beyond the maximum engagement range of the ADCAP torpedo. In addition, Sea Lance was to provide expanded engagement opportunities against high speed transiting and evading submarines.