Which factor primarily influences the buoyancy of a diver?

The buoyancy of a diver is primarily influenced by the volume of air in the Buoyancy Control Device (BCD). When a diver adjusts the amount of air in the BCD, they can increase or decrease their buoyancy. By adding air, the diver becomes more buoyant and is able to ascend, while releasing air allows for a decrease in buoyancy, enabling the diver to descend or achieve neutral buoyancy at a desired depth.

While the weight of the diver does affect buoyancy, it is the adjustment of air in the BCD that directly controls buoyancy during a dive. Water temperature can influence body heat retention and comfort but does not significantly affect buoyancy itself. The thickness of a wetsuit does contribute to buoyancy by providing insulation and adding buoyant material, but the most immediate and effective way to manage buoyancy underwater is through the manipulation of air within the BCD.