With the snow starting to recede in my part of the planet, the mind starts having visions of warmer weather activities. In my particular case, I love to spend a weekend afternoon out in my boat with a pole in my hand, trying to determine if there was anything hungry for worms in the water beneath me.
When out in the boat, it is vitally important (in fact it's the law in my country) to have certain safety equipment on your boat at all times. Besides the usual life jackets, flashlights, and tow ropes, you are supposed to have some sort of sound signaling device. In the little safety kit that I bought for my boat, that came in the form of a small whistle that you are supposed to blow into to signal for help.
Personally, I found the whistle a bit lacking in the sound volume department, but to be quite frank, installing an air horn on a small 14-foot boat with an outboard motor seems a bit ridiculous.