If you ascend 10 feet without deflating after using 0.10 cubic feet of air for neutral buoyancy at 30 feet, what will happen to your buoyancy?

When you ascend in the water column, the pressure around you decreases. This reduction in pressure allows any trapped air in your buoyancy control device (BCD) or body to expand. At 30 feet, the pressure is approximately 1.5 atmospheres (1 atm of surface pressure + 0.5 atm from the water column). As you ascend to 20 feet, the pressure drops to about 1.25 atmospheres.

If you have not deflated your BCD after using 0.10 cubic feet of air for neutral buoyancy at 30 feet, that volume of air will expand as the pressure decreases. Due to Boyle’s Law, which states that the volume of a gas is inversely proportional to the pressure applied to it, the 0.10 cubic feet of air will increase in volume. This increase results in increased buoyancy, leading to a greater tendency for you to float.

Therefore, your buoyancy will shift from neutral to positively buoyant as you ascend, making the option of increased positive buoyancy correct. Understanding the dynamics of pressure and gas volume is essential for managing buoyancy and ensuring safe diving practices.