Systems, methods, and apparatus for desalinating water are provided. In the figures, a pile head member 5 is provided to the pile head 2a of the foundation pile 2, a structure support member 6 is fixed to an upper structural portion 3, and these mutually contact one another in the vertical direction via a first contacting surface 11 which defines a portion of a first imaginary spherical surface Sv1. Consequently, the invention can effectively allow the power source of a conducting wire of the sieve of the aquarium to avoid getting into the container of the water tank; in addition, it can eliminate the possibility of electric leakage of said conducting wire underwater in the container of the water tank. The horizontal translation alleviates much of the stress imparted to doors on aircraft which move to vertical positions in or extending from the aperture in the fuselage.