What signal indicates a diver is in trouble?

A diver in trouble often signals for help by waving their arms repeatedly. This motion is widely recognized as a call for assistance and grabs the attention of other divers and surface personnel. When a diver waves their arms, it indicates distress or a need for help, which should prompt immediate awareness and action from nearby divers or emergency responders.

While splashing water can sometimes indicate trouble, it is not a universally recognized signal and may not be specific enough. Submerging without resurfacing, while a clear indicator of a problem, does not serve as an active signal, as it can lead to more serious consequences by the time assistance is initiated. Throwing equipment may suggest panic or distress, but it’s not a standardized or clear signal of a diver needing help. Waving arms is a recognized method of communication, making it the best choice for indicating that a diver requires assistance.