What is one way to signal distress underwater at night?

Using a series of quick, repeated flashes from your dive light is an effective way to signal distress underwater at night. This method is particularly suitable for low visibility environments, as the light can be seen from a distance and can attract the attention of fellow divers. Additionally, light signals can be easily distinguished from other movements or phenomena in the water, making it a reliable means of communication in an emergency situation.

In the context of night diving, where visibility is limited, signaling with light ensures that your distress signal stands out to others who may be nearby. This technique takes advantage of the equipment you already have, allowing for quick and efficient communication without the need for complex gestures or movements that might be difficult to interpret in poor visibility conditions.

The other options may not effectively convey distress: yelling underwater is ineffective due to sound being poorly transmitted in water, swimming to the surface quickly can increase the risk of injury or decompression sickness, and hiding behind a coral structure would reduce your visibility to potential rescuers and may cause confusion about your actual status.