Which statement about ambient pressure and depth is correct?

• A. Ambient pressure decreases with depth.
• B. Ambient pressure remains constant with depth.
• C. Ambient pressure increases with depth.
• D. Ambient pressure varies unpredictably with depth.

Answer: (C)

Ambient pressure is the pressure in the surrounding water acting on you, which equals the atmospheric pressure at the surface plus the hydrostatic pressure from the water column above. Since the weight of the water increases with depth, the hydrostatic component grows, so the total ambient pressure increases as you go deeper. At the surface you have about 1 atmosphere of pressure, and seawater adds roughly another atmosphere for every 10 meters of depth. Therefore, deeper means higher ambient pressure. The other statements don’t fit because pressure does not decrease with depth, remain constant, or vary unpredictably—it follows a predictable increase with depth in a fluid at rest.