Depth-tolerant, inflatable, variable-buoyancy buoy

A buoy, comprising a body, an inflatable bladder, a bladder cover, a pressure vessel, a variable-volume, gas-filled chamber, a controller, a compressor, and a ballast. The bladder cover surrounds the inflatable bladder. When the inflatable bladder is deflated, the bladder cover is configured to compress the inflatable bladder so as to conform to an exterior contour of the body. The variable-volume, gas-filled chamber provides passive, variable buoyancy to the buoy. The controller is configured to control a transfer of compressible gas between the inflatable bladder and the first pressure vessel. The compressor is configured to remove gas from the inflatable bladder, compress the removed gas, and introduce the compressed gas to the first pressure vessel for storage. The ballast maintains a substantially vertical orientation of the buoy when the buoy is in water.