Hydraulically-actuated cable cutter

A hydraulically actuated cable cutter, comprising a cable holder, a cable cutting member in the holder adapted to be driven forward to cut a cable, an explosive charge for driving said member forward, a firing pin slidably mounted in said holder behind the charge for detonating it, a spring urging the pin forward toward the charge, a firing pin retractor slidably mounted in said holder behind said pin and detachably connected with the pin for retracting it a predetermined distance to compress said spring, the connection between the retractor and firing pin being such that when the pin has been retracted said predetermined distance the retractor will release the pin, a cylinder separate from the cable holder spaced behind said retractor and having a front end and a closed rear end, a piston in the cylinder normally spaced from its opposite ends, tension means extending through an opening in the front end of the cylinder and connecting said retractor with the piston, the cylinder being intended for submersion in a body of water and having an opening for the water between its front end and the piston, whereby a predetermined increase in water pressure at the cylinder will move the piston rearwardly therein to retract said retractor until the firing pin is released.