If scuba diving or snorkeling, what should you do when all divers and snorkelers are back in your vessel?

When all divers and snorkelers are back in the vessel, ensuring that the vessel operator is aware is crucial for safety and coordination. This step helps to make sure that the operator is fully engaged with the situation and can respond appropriately, whether that means signaling for departure, checking equipment, or ensuring that everyone is accounted for.

In marine environments, communication is vital. The operator must know that all divers are safely aboard to avoid accidentally starting the engine or departing without ensuring that everyone is accounted for, which could lead to dangerous situations. Being aware also allows the operator to assess any immediate needs of the divers that may have arisen during their time in the water, such as medical attention or hydration.

The other choices involve procedures that may be relevant but should only occur after confirming the safety and presence of everyone on board. For example, signaling for departure and starting the engine could lead to potential accidents if done before confirming that all team members are safely back and secure. Checking the divers-down warning device is also important but comes after ensuring that safety protocols regarding everyone being back on the vessel are established.