Which pressure is equivalent to 2 ATA at sea level?

• A. 32 feet
• B. 33 feet
• C. 64 feet
• D. 66 feet

Answer: (D)

To understand the pressure equivalent to 2 ATA (Atmospheres Absolute) at sea level, it is essential to recognize how atmospheric pressure changes with depth in a body of water. At sea level, the atmospheric pressure is approximately 1 ATA. When diving underwater, pressure increases by approximately 1 ATA for every 33 feet of seawater depth.

Therefore, at a depth of 33 feet, the pressure would be 1 ATA (water pressure) plus the 1 ATA of atmospheric pressure at sea level, totaling 2 ATA. This means that at 33 feet, a diver experiences a total pressure equating to 2 ATA.

The answer indicating 66 feet is incorrect because at that depth, the pressure would actually be 3 ATA, which is the sum of 2 ATA for the water pressure (2 x 33 feet) plus the 1 ATA of atmospheric pressure at sea level. Thus, recognizing that each additional 33 feet adds another ATA reinforces why 33 feet is the correct correlation for 2 ATA.