Benefits of Nitrox
Nitrox contains less nitrogen than standard air. This means that as you dive, your body ingasses less nitrogen than it would with standard air. As a result, you can spend more time at a specific depth without developing decompression sickness. The increase in bottom time depends on the oxygen percentage of the nitrox mixture.

Another benefit is reduced surface interval times. This is extremely beneficial when visiting deeper dive sites from a boat. The boat's schedule might not allow for extended surface intervals, which means divers using air may have to cut their second dive short in order to prevent exceeding their no-decompression limits. But with Nitrox, the reduced nitrogen ingassing reduces the required surface interval time between dives, which allows for longer repetitive dives.