Abstract: A new method for making large underground storage caverns in bedded or domal salt deposits for the storage of fluid materials in areas where solution mining water temperatures are low by a process which significantly reduces the amount of time required to make equivalent sized underground storage caverns and which is economically feasible and friendly to the environment. The process includes the warm water solution mining of the underground salt deposits in a manner which conserves the heat contained in the supernatant brine from the underground cavity and employs this heat as a significant source for warming the water employed in the solution mining operation.