What must a diver have in communication with the dive supervisor when using underwater tools?

In underwater operations, effective communication between the diver and the dive supervisor is crucial for safety and operational efficiency. When divers are using underwater tools, they can encounter various hazards and need to be able to communicate any issues, changes in plan, or emergencies effectively.

The use of communication devices, often referred to as "comms," allows for real-time dialogue, ensuring that the supervisor is aware of the diver's situation and can provide guidance or assistance as needed. This immediate line of communication can prevent accidents and ensure that the dive follows safety protocols and procedures.

While emergency oxygen, a surface marker buoy, and a dive compass have their specific uses, they do not facilitate direct communication in the way that comms do. Emergency oxygen may be used in case of an incident, but it does not support ongoing communication. A surface marker buoy is used to mark the diver's location and does not convey messages. A dive compass assists in navigation but does not aid in verbal or message-based communication. Therefore, having a reliable communication system is essential for the successful and safe operation when a diver is using tools underwater.