Do scuba divers use one tank or two?

Scuba divers typically use one tank, which is sufficient for most recreational diving activities. However, for deeper dives or longer durations, some divers may opt to use two tanks for increased air supply and safety. This setup can also be useful in technical diving or in situations where redundancy is critical. Ultimately, the choice between one or two tanks depends on the dive plan and the diver's experience level.