Watertight doors are special types of doors found on the ships which prevent the ingress of water from one compartment to other during flooding or accidents and therefore act as a safety barrier.

It limits the spread of water inside the vessel. These doors are used onboard in many ships such as in the fore and aft passageways underdeck and in engine room bulkheads leading to shaft tunnels in container vessels, large passenger ships, offshore vessels, oil exploration vessels