Signaling devices, such as whistles, strobe lights, and mirrors, are used to attract attention and signal for help during a dive. Whistles are useful for producing loud sounds that can be heard from a distance, while strobe lights provide visual signals that can be seen in low-light conditions or from the surface. Mirrors can reflect sunlight to signal surface vessels. These devices should be easily accessible and in good working condition. Regular checks and practice in using signaling devices help ensure they are effective in emergency situations.