To provide techniques for effectively forming closed spaces of various shapes in which people can stay by connection of a plurality of floatable flat floats and for utilizing the closed spaces as vehicles floating on the surface of water, thus solving the problem with rubber boats and life buoys that the boats and buoys usually used in rescue operation and leisure have some drawbacks as vehicles for safely protecting people, and to provide a means and a structure for simplifying interconnection of the plurality of flat floats to form a three-dimensional structure.

Connectable hexagonal flat floats inflated by gas filling and each forming a hexagonal flat plate shaped so that its external angles are all inscribed in a circle at angle of 60 degrees, e.g. a flat plate in the form of a regular hexagon, so that they can be floated on the surface of water, are connected to one another to form a connecting type three-dimensional construction of a shell structure in the form of a rugby ball, tire, hemispherical dome, etc.