Abstract: A floating container cap for liquid storage containers used adjacent to bodies of water or similar liquids, the storage containers having a cylindrical input port of a predetermined internal diameter with a threaded surface for interaction with the container cap, comprising a cylindrical housing which is fluid tight with an external diameter less than the container input port. A generally circular metallic top having a diameter larger than the remainder of the housing forms a top end of the housing and a foam material is disposed inside the housing. To removably secure the cap in place, a plurality of threads are disposed on the outside of the housing adjacent to the top for interfacing with the input port threaded surface.