What are the four basic divisions of gas during a dive?

The concept of gas management in diving revolves around ensuring that a diver uses their gas supply efficiently and safely throughout the dive. The correct answer identifies the four basic divisions of gas during a dive as outbound, return, ascent, and reserve.

When divers plan their gas usage, they categorize it into the outbound portion (the gas used while descending and reaching the planned depth), the return portion (gas allocated for the journey back to the surface or designated stops), the ascent portion (gas needed to safely ascend to the surface, including any safety stops), and the reserve, which is critical for emergency situations. The reserve serves as a safety buffer, ensuring that divers have sufficient air to manage unexpected circumstances.

Each of these categories plays a vital role in a diver's planning and execution, promoting safety and preparedness. Understanding these divisions helps divers calculate their air consumption rate, manage their gas effectively, and maintain safety throughout the dive.