What should a Divemaster's first action be upon finding an unresponsive diver?

When encountering an unresponsive diver, the first action should be to check for breathing and pulse. This step is critical in assessing the diver's condition and determining the appropriate response. By checking for these vital signs, the Divemaster can quickly ascertain whether the diver is experiencing serious medical distress, such as a cardiac arrest or respiratory failure, which requires immediate action.

This assessment allows for informed decision-making regarding the next steps, such as calling for help or starting CPR. It is essential to have accurate information before initiating a potentially life-saving intervention. Starting CPR without checking might waste precious time if the diver is breathing or has a pulse. Similarly, signaling other divers to surface may not address the immediate needs of the unresponsive diver and could result in further complications. Therefore, verifying the diver's condition is the foundation for effective emergency response in diving incidents.