During a dive, your regulator begins to free-flow. What should you do?

When a regulator begins to free-flow during a dive, the safest procedure is to alert your buddy and together make a controlled ascent to the surface. This approach ensures safety by maintaining communication and support, especially since free-flowing regulators can lead to the depletion of your air supply. By ascending together, both divers can monitor each other’s buoyancy and ensure that the ascent is controlled, mitigating the risk of rapid ascents that could result in decompression sickness or other hazards.

Making an emergency ascent or attempting to buddy breathe are less safe practices in this scenario. An emergency ascent can lead to uncontrolled ascent rates and the associated risk of injury, and buddy breathing is often not feasible or safe in situations where equipment failure occurs. Additionally, completing the task without addressing the free-flowing regulator compromises the diver's safety and could lead to a critical air supply situation. Hence, the emphasis on a controlled ascent with buddy support is the most prudent response.