What critical task must a Dive Supervisor perform concerning the diver's equipment?

The critical task of calculating the time available for tanks is fundamental for a Dive Supervisor because it directly impacts diver safety and operational efficiency during a dive. Proper tank management, including calculating how long the air supply will last based on the divers' depth, breathing rates, and the size of the tanks, ensures that divers will have enough air to complete their tasks and safely return to the surface. This calculation is crucial for establishing dive plans and ensuring adherence to bottom time and no-decompression limits.

Monitoring buoyancy control, providing emotional support, and ensuring divers are aware of their surroundings, while important aspects of a dive supervisor's role, do not directly involve the critical management of air supply, which can lead to life-threatening situations if not correctly managed. The focus on tank time assessment reflects the Dive Supervisor's responsibility for maintaining the safety of the dive operation as a whole.