The ambient pressure at 10 meters (33 feet) is approximately:

• A. 1 bar
• B. 3 bar
• C. 2 bar
• D. 4 bar

Answer: (C)

Ambient pressure increases as you go deeper because water adds pressure on top of the atmospheric pressure at the surface. At the surface you’re around 1 bar. In seawater, the pressure increases by about 1 bar for every 10 meters of depth. So at 10 meters (33 feet), you add roughly 1 bar of water pressure to the surface 1 bar, totaling about 2 bar. That’s why 10 meters corresponds to about 2 bar, and 33 feet is about the same depth.

The other numbers would correspond to deeper or shallower depths: 1 bar is just at the surface, 3 bar would be around 20 meters, and 4 bar around 30 meters.