What are the two factors that have the greatest effect on gas consumption during a dive?

The factors that have the greatest effect on gas consumption during a dive are depth and diver activity. As a diver descends to greater depths, the pressure increases, which affects the volume of gas in the diver's lungs and how the body metabolizes oxygen. This increase in pressure generally leads to a higher consumption of gas due to the increased effort required to compensate for the surrounding pressure and to maintain buoyancy.

Additionally, diver activity plays a significant role in gas consumption. When a diver is engaged in strenuous activities, such as swimming against a current or performing tasks, their metabolic rate increases, leading to greater oxygen demand and, consequently, higher gas consumption. Conversely, during periods of rest or minimal activity, the gas consumption decreases significantly. Understanding these two key factors helps divers manage their air supply effectively and plan their dives safely.