A support of deep caisson type having a longitudinal axis, for floating installation in a body of water and provided with mooring lines for anchoring to a seabed, has a lower portion in the body of water having a weight element, an upper portion that supports a platform above a water surface, and an extended portion in an area between the upper portion and the lower portion. The extended portion has one or more internal storage chambers and one or more ballast chambers. The storage chambers are arranged closer to the longitudinal axis than the ballast chambers.