Abstract: A floating structure to support maritime operations is constituted by a metallic platform, in the shape of an internally open square (10) floating in the ocean being moored to the bottom of the ocean by a cable system (C.sub.1, C.sub.2, C.sub.3 . . . C.sub.n) tied to a pile system (E.sub.1, E.sub.2, E.sub.3 . . . E.sub.n). It retains in its interior a portion of the sea which is communicated to the outside ocean through an opening (11) in the walls of the said metallic platform (10) in such a way that, in that confined part of the ocean, the support boats to the sea work, may be moored due to the fact the interior of the open square is calm in respect to the rough sea outside the structure (10).