Wet mateable connector

An underwater connector has mateable plug and receptacle units each containing a member having an internal chamber enclosing a contact element when the units are unmated. The members each have a resilient forward end portion with an opening communicating with the chamber, and a forward end face in sealing engagement with the corresponding end face of the other member to provide a seal when the units are mated. An actuator in each unit compresses the forward end portion of each member to close and seal the opening, and the arrangement is such that the forward end portions move away from the actuators and open as the units are mated, to permit one contact element to pass into the member of the other unit for connection to the other contact element. The forward end portions of the members are self-sealing in both the mated and unmated condition, requiring no additional seal elements.