An apparatus for servicing one or more water vessels, in particular, the invention is directed towards an autonomous replenishment buoy for fueling one or more water vessels. The autonomous replenishment buoy has a first configuration when not servicing water vessels, and a second configuration when performing fueling or other servicing functions. The autonomous replenishment buoy may float at the surface of the water, or may be moored beneath the surface of the water in the first configuration when not servicing water vessels. The autonomous replenishment buoy may transform from the first configuration to the second configuration to perform fueling and other services on water vessels.