The buoyancy compensator is one of the items of diving equipment most requiring skill and attention during operation, as control is entirely manual, and adjustment is required throughout the dive as weight reduces due to gas consumption, and buoyancy of the diving suit and BCD varies with depth. Fine buoyancy adjustment can be done by breath control on open circuit, reducing the amount of actual BCD volume adjustment needed, and a skilled diver will develop the ability to adjust volume to maintain neutral buoyancy while remaining aware of the surroundings and performing other tasks. The buoyancy compensator is both an important safety device when used correctly, and a significant hazard when misused.