To avoid stage decompression after a dive to 70 feet for 35 minutes, what is the minimum surface interval required?

The proper minimum surface interval after a dive is crucial to reduce the risk of stage decompression when diving at a depth of 70 feet for 35 minutes. The answer of 1 hour and 16 minutes aligns with standard dive tables and decompression software guidelines for this specific dive profile.

During a dive, the body absorbs nitrogen at increased rates due to higher pressures, and the longer the dive lasts, the more nitrogen is absorbed. A surface interval allows for the gradual release of this nitrogen as the diver ascends back to the surface pressure. For a dive of this nature, 1 hour and 16 minutes gives enough time for the body to off-gas a significant amount of nitrogen, minimizing the risk of decompression sickness.

In comparison, shorter surface intervals such as 30 minutes or 1 hour would not adequately account for the nitrogen levels that the diver would carry after such a dive, thereby potentially leading to decompression obligations. While a 2-hour interval may seem cautionary, it exceeds the minimum requirement established by dive tables for a maximum safety margin, making 1 hour and 16 minutes the appropriate answer for this scenario.