Abstract: The invention relates to an underwater cable cutting device which is used in combination with a geophysical exploration apparatus carrying a depth control unit. The depth control unit is provided with guiding planes which are protected by the cable cutting device mounted ahead of the depth control unit. The cutting device has a generally flat body having a curved forward portion and a pair of hook-shaped cutting portions on opposite rearwardly extending sides of the flat body for deflecting a cable from the depth control unit and severing the cable or mooring line with its cutting surface formed by the hooked-shaped cutting elements. The device is attached to an elongated housing and abuts a securing shank of the depth control unit, without requiring any modifications to be made to the depth control unit.