If a diver's surface air consumption rate is 30 psi per minute (2.1 bar per minute), what would be his/her consumption rate at 66 feet (20.11 m) of seawater?

To determine a diver's consumption rate at a depth, it is essential to understand how pressure affects air consumption. At sea level, the atmospheric pressure is 1 atmosphere (which is roughly 14.7 psi). For every 33 feet (approximately 10 meters) of seawater, the pressure increases by an additional atmosphere, which means the pressure at 66 feet (20.11 meters) is about 3 atmospheres (1 atmosphere at the surface plus 2 additional atmospheres from the water pressure).

When underwater, the volume of air consumed increases in relation to the surrounding pressure. Therefore, air consumption at depth can be calculated by multiplying the surface air consumption rate by the total pressure in atmospheres.

In this case, the surface air consumption rate is 30 psi per minute. At 66 feet, the pressure is 3 atmospheres, so the consumption would be:

30 psi/minute (surface) × 3 (atmospheric pressure at 66 feet) = 90 psi per minute.

Thus, at a depth of 66 feet, the diver would indeed have a consumption rate of 90 psi per minute. This demonstrates the importance of accounting for depth in scuba diving calculations to ensure proper air supply management.