Apparatus for solution mining and gas storage in a salt cavern formed by solution mining comprises a flow diverting conduit string is provided in fluid communication with two or more concentric conduits within the single main bore, with at least one lateral opening from an internal passageway with an outer annular passageway communicating with the surface under a single valve tree. Flow control devices, flow diverters and/or isolation conduits can be inserted into the flow diverting conduit string, enabling a dissolution zone in the salt cavern to be varied to control the shape of the cavern. Furthermore the flow diverting conduit string used to form the cavern can also be used for dewatering and gas storage.