A connector for connecting together in a water-tight housing various optical instruments of an underwater or submarine arrangement having optical fiber cables. The connector is constructed in a manner such that a plug containing the terminals of optical fiber cables is connected in an easily attachable/detachable fashion to a receptacle which is mounted on the water-tight housing. Sealing material is interposed between the water-tight housing and the receptacle and between the receptacle and the plug for preventing the infiltration of water or sea water into the water-tight housing.
