When they are inactive, the floodgates rest on the seabed, completely hidden, with the hollow section completely flooded with sea water. In case of high tide air pressure is injected in the floodgates hollow section to substitute water with air, allowing the floodgates to rotate on their axes and emerge from the seabed, creating a defensive barrier that stops the tide. The floodgates remain active only for the length of the high tide event.