What is the purpose of the diver's buoyancy compensator?

The purpose of a diver's buoyancy compensator, commonly referred to as a buoyancy control device (BCD), is primarily to adjust the diver's buoyancy underwater. This is essential for maintaining neutral buoyancy, which allows divers to hover at a desired depth without having to expend energy to swim up or down. By adding or releasing air from the buoyancy compensator, divers can fine-tune their buoyancy to achieve optimal control of their position in the water. This capability facilitates better stability, comfort, and energy efficiency while diving, as divers can position themselves accurately without constantly adjusting their body positioning or using their limbs excessively.