Which depth has the longest single depth limit of 240 minutes?

Which depth has the longest single depth limit of 240 minutes?

• A. 30 fsw
• B. 40 fsw
• C. 35 fsw
• D. 25 fsw

Answer: (D)

The key idea here is no-decompression limits: the amount of time you can stay at a single depth without needing to perform decompression stops on ascent. The shallower the depth, the longer the no-decompression limit tends to be, because less nitrogen is absorbed into the tissues at that depth. Among the depths listed, the shallowest is 25 fsw, and at that depth the no-decompression limit is 240 minutes—the longest allowed bottom time without decompression. Deeper depths—30, 35, and 40 fsw—have shorter no-decompression limits, so they do not reach 240 minutes. Therefore, 25 fsw is the correct choice.

The key idea here is no-decompression limits: the amount of time you can stay at a single depth without needing to perform decompression stops on ascent. The shallower the depth, the longer the no-decompression limit tends to be, because less nitrogen is absorbed into the tissues at that depth.

Among the depths listed, the shallowest is 25 fsw, and at that depth the no-decompression limit is 240 minutes—the longest allowed bottom time without decompression. Deeper depths—30, 35, and 40 fsw—have shorter no-decompression limits, so they do not reach 240 minutes. Therefore, 25 fsw is the correct choice.