A fuel depot and method autonomously and clandestinely provide fuel for transiting ships. An elongate streamlined flexible bladder member has flexible hull walls and divider walls separated by uniform spaces to form fuel compartments having a fuel valve and fuel pump. The bladder member can transit submerged to a remote destination. A fuel and water tight composition in and along the spaces prevent fuel and water leaks to ambient water and between the compartments. A submersible propulsion system has propulsive machinery and steering gear for towing the bladder member. A command/control system on the submersible propulsion system generated and couples driving signals to the propulsion system to tow and steer the bladder member to the remote destination using the preprogrammed computer, inertial navigation system (INS), global positioning system (GPS), and RF transceiver of the command/control system.