I tried the clicker idea a few weeks ago in the Keys, but didn't have much luck myself. I told my dive buddy the day before that I was going to try it so that he might be aware of it in the water. During the dive I would periodically start clicking it and watched for him or any other divers nearby to start looking around for the source of the sound. Nothing. You could hear it but isn't loud enough to snap a diver out of their underwater trance.