Which of the following limits should be established prior to every scuba dive?

• A. Minimum air pressure, maximum bottom time
• B. Maximum bottom time
• C. Maximum bottom time, maximum depth, minimum air pressure
• D. Maximum depth and surface interval

Answer: (C)

Pree-dive planning hinges on setting three limits to control risk: how deep you’ll dive, how long you’ll stay at that depth, and how much air you’ll keep in reserve. The depth limit protects you from going beyond what your training, gear, and gas management permit, and helps manage nitrogen loading. The bottom-time limit is tied to depth because the deeper you go, the faster inert gas accumulates, so you need a plan that respects no-decompression limits or your dive computer’s limits. The minimum air pressure creates a safety reserve so you can safely ascend, perform any required stops, and handle unexpected situations or assist a buddy if needed. Together, these three limits provide a safe, controlled dive plan. The other options omit one or more essential elements (for example, omitting a depth limit or an air reserve, or focusing on surface interval which is planning for multiple dives rather than the single dive at hand).