The Storm Whistle is claimed to be the world's loudest whistle. Made with a special harmonic chamber, it is totally waterproof and can even be heard and used underwater. When blown, the chamber automatically purges all water so it instantly becomes usable (and noisy).
A basic part of every divers safety kit, this is a simple and effective way to be found when drifting away from the boat or search and rescue are looking for you. Hopefully you should never have to use it, but when you need it you want it to work!
We sell this in flourescent green, black, and orange.