According to IANTD air dive tables, if you dive to 15 meters (49 feet) for 45 minutes, what surface interval is required for a dive to 10 meters (33 feet) for 30 minutes?

To determine the required surface interval after a dive to 15 meters (49 feet) for 45 minutes before a subsequent dive to 10 meters (33 feet) for 30 minutes, one must consult the IANTD air dive tables, which assess nitrogen absorption and the corresponding surface intervals needed for safer subsequent dives.

The correct answer indicates that a 35-minute surface interval is necessary. This is based on the cumulative nitrogen loading that occurs during the first dive. A dive to 15 meters for 45 minutes contributes to a certain level of nitrogen saturation, which must be accounted for when planning a second dive to a depth of 10 meters for 30 minutes.

Depth and duration of dives are critical in calculating the no-decompression limits and necessary surface intervals since they impact how much nitrogen is absorbed into the body's tissues. Failure to allow adequate surface time could lead to an increased risk of decompression sickness due to residual nitrogen. Following proper guidelines helps ensure diver safety by allowing the body to off-gas excess nitrogen before undertaking another dive.

Thus, the requirement for a 35-minute surface interval ensures that the diver maintains safety while transitioning to a shallower dive following a deeper and longer initial dive.