Abstract: In improved cable cutter for undersea use is presented which has a self-cained, pressure compensated hydraulic system which allows it to operate in the deep ocean. The cable cutter is designed to operate from and mate with manipulators of Navy deep submergence vehicles. The concept of this cable cutter is a closed hydraulic system which provides driving force on a piston pushing a cutting blade against an anvil. The hydraulic power is provided by an internal gear pump. The gear pump has a drive shaft which mates with the rotary output of a deep submergence vehicle manipulator. The hydraulic fluid reservoir also serves as a pressure compensator for working in the deep ocean. The hydraulic fluid system comprises a main cylinder which contains the drive piston and a secondary cylinder which consists of a flexible tube that allows fluid pressure equalization with the environment as well as volume compensation. Both cylinders are mounted between manifold components.