A variable buoyancy buoy and method for deployment therefor can include a fixed buoyancy portion formed with a cavity and an enclosure. A pressure hull containing instrumentation can be place in the cavity, and a variable buoyancy portion that can be inserted into the enclosure. The fixed buoyancy portion can have a spar buoy configuration or a marker buoy configuration, and can further be formed with at least one opening to establish a path of fluid communication between the exterior of the buoy and the enclosure. The variable buoyancy portion can be a compressible bladder, or compressible foam, which can change form a maximum volume at the water surface to a minimum volume as the buoy descends towards stowage depth. The decrease in buoyancy facilitates retrieval of the buoy by an apparatus on the ocean floor.