Which physiological change occurs as a diver ascends to the surface after a dive?

As a diver ascends to the surface after a dive, increased buoyancy occurs primarily due to the decreasing pressure surrounding the diver as they rise. At greater depths, the pressure is higher, which allows a diver to maintain neutral buoyancy with the help of their buoyancy control device (BCD) and adjustments in body position. As the diver ascends and the pressure decreases, the volume of air in the BCD, lungs, and any other air spaces will expand. This increase in volume leads to increased buoyancy, which can cause the diver to rise more quickly toward the surface if not managed appropriately.

Other physiological changes during ascent include variations in heart rate and the elimination of gases like nitrogen, but these changes do not result in increased buoyancy. Therefore, recognizing that increased buoyancy is a direct consequence of ascend-related pressure changes is crucial in understanding the dynamics of diving and the necessary skills to control ascent rates effectively.