Very Loud Whistle

After looking around on the internet, I saw that there was a very loud whistle called the Storm Whistle. It is an emergency whistle that is very loud that can be heard "up to 50 ft underwater." The other whistle that I used for inspiration is the Aztec Death Whistle. The Death Whistle was used as an intimidation for the Aztec warriors. The whistles sound like a very loud scream, and the warriors usually had up to a thousand of them being blown at once charging into battle. Both of these real life whistles were inspiration to make this whistle.