The minimum surface interval recommended between two dives is ______ minutes.

The minimum surface interval recommended between two dives is ______ minutes.

• A. 20
• B. 45
• C. 30
• D. 60

Answer: (D)

The key idea is that between dives you need time on the surface for nitrogen to off-gas from your tissues. A 60-minute surface interval is a conservative minimum that allows a meaningful amount of off-gassing before the next dive, helping reduce the risk of decompression sickness on a second dive the same day. Shorter intervals leave more nitrogen in the body and increase risk, while longer intervals further reduce that risk. In recreational diving, 60 minutes is a common standard to use as the minimum between dives on a single day, especially after deeper or longer first dives.

The key idea is that between dives you need time on the surface for nitrogen to off-gas from your tissues. A 60-minute surface interval is a conservative minimum that allows a meaningful amount of off-gassing before the next dive, helping reduce the risk of decompression sickness on a second dive the same day. Shorter intervals leave more nitrogen in the body and increase risk, while longer intervals further reduce that risk. In recreational diving, 60 minutes is a common standard to use as the minimum between dives on a single day, especially after deeper or longer first dives.