A prefabricated floatable offshore island structure

A prefabricated multi-use offshore island structure is described which is designed to operate in floating condition, as a semisubmerged stable platform, or as a small waterplane gravity caisson supported structure. Unique features are the modular design of the gravity caissons, and the self anchoring as well as self levelling capability designed into the gravity caissons which permit placement of the island structure on uneven bottom terrain. It similarly permits the injection of non-compressible fillers or cementing agents under the caisson voids, to allow placement on soft, low load bearing soils by effective load distribution, and/or local hardening of the bottom soils.