Submerged offshore storage facility

Method for subsea storage of a liquid having a lesser density than water, within a submerged storage tank having a storage compartment, and an overflow compartment communicated therewith, which method includes the steps of;

• maintaining said submerged storage compartment full of water and said liquid having a lesser density than water,
• communicating the lower section of said storage compartment with the surrounding water to permit passage of the water to and from said tank storage compartment,
• periodically introducing an amount of the less dense liquid into the storage compartment whereby to depress the level of the less dense liquid therein so as to discharge a stream of said water from the storage compartment lower end, said stream having a minor amount of the less dense liquid carried therewith,
• passing said stream of displaced water and lighter liquid into said overflow compartment whereby to change the stream's directional flow,
• permitting the respective liquids to separate in said overflow compartment whereby the lighter liquid rises to the surface, and the water continues through said overflow compartment, and
• periodically removing the lesser density liquid from said overflow compartment, thereby avoiding inadvertent pollution by the less dense liquid, when water from the overflow compartment is passed to the seawater in which the storage tank is submerged.