Abstract: A semi-submergible spherical residential structure adapted to be floated in a body of water. The structure features a substantially spherical shell having a hollow annular sponson affixed around its maximum girth such that the sponson is parallel to the water surface when the structure is floating in a body of water. The outer diameter of the sponson is sufficiently large so as to stabilize the shell when floating and the sponson has a width which is sufficiently great so as to provide adequate reserve buoyancy to the structure when the latter is weighted.