What is the recommended surface interval after extended dives with Nitrox?

The recommended surface interval after extended dives with Nitrox is 120 minutes. This surface interval allows the body adequate time to off-gas excess nitrogen that may have accumulated during the dive. For extended dives, especially those that exceed typical recreational dive limits, longer surface intervals help to reduce the risk of decompression sickness and improve overall safety.

Nitrox, which has a higher concentration of oxygen and lower nitrogen compared to air, can alter the dynamics of nitrogen absorption and elimination in the body. While it generally allows for longer no-decompression limits, it is still crucial to adhere to proper surface intervals and dive planning. The 120-minute interval provides a buffer, especially after more challenging dives, ensuring that divers can safely continue their diving activities or conclude their trip without increased risks.

The other choices, while potentially shorter intervals, do not provide sufficient time for off-gassing in the context of extended diving with Nitrox. These shorter intervals could leave divers at a higher risk for residual nitrogen build-up in their tissues, particularly after deep or long-duration dives.