A while back, my daughter sent me several survival items for my birthday; one of them was the Storm Safety whistle. This is by far the loudest whistle that I have ever encountered. My grandkids and wife scatter when they see me coming with it because it is so loud. They say it hurts their ears.
After having played with it for a while, I have found the good and the bad. The good it is the loudest whistle you will ever hear, it is probably twice as loud as a normal whistle. The bad it is a about twice the size of a normal whistle and everybody runs when you get it out.
I haven’t had a chance to try this yet but the company and many dive clubs claim that it can be heard under water, up to 50 feet away.
According to the manufacturer, “the loudness of the Storm safety whistle was derived in a soundproof chamber by a research team at the Institute for the Deaf in St. Louis Missouri. The Decibel reading
varied between 118 and 120 dB. We compared the loudness of the Storm whistle, Windstorm whistle and a number of our competitor’s whistles. The Storm whistle was nearly twice as loud as any other whistle”.
After playing with this one, I am going to order several more for women in my family to carry in their purses and put in their packs. I spend a lot of time in the mountains and normally carry a small pack in case I get lost or have a problem, This whistle is going in my pack. They cost $5.50 each and are made in the USA. http://www.stormwhistles.com/