What is a common signal for a diver experiencing difficulty?

The correct signal for a diver experiencing difficulty is the "upside-down" signal or flashing the light repeatedly. This signal indicates that the diver is in distress or facing an emergency situation. The practice of using an upside-down signal is designed to attract attention quickly and show that the diver requires immediate assistance.

Flashing a light repeatedly can also enhance visibility in low-light conditions, ensuring that other divers or surface support can easily recognize that there is a problem. This communication method is vital as it facilitates prompt responses from dive buddies or support staff, ensuring the safety of the diver in trouble.

In contrast, other signals like the "thumbs up" gesture typically indicate that a diver is okay and ready to ascend, while the "peace" sign has no established meaning in diving contexts. The "no air" signal is more focused on a specific issue related to air supply, rather than a general distress signal. Therefore, the upside-down signal or repeated light flashes effectively communicates a broader range of emergencies faced during a dive.