Whistle while you work
Still spoken on the Spanish island of La Gomera, Silbo Gomero is a language that consists entirely of whistling.
“Originally developed to allow communication at distances of up to 5km through the mountainous island’s valleys, Silbo Gomero is regular Spanish transposed into simplified, short whistling sounds. Its efficiency and usefulness for outdoor workers helped it survive into the modern era.”
It was once considered a language of peasants and so people stopped using it. It enjoyed a comeback in the 90s and is now cherished part of the Gomeran culture. UNESCO has officially pledged to protect the language as an example of intangible cultural heritage.
https://blog.pimsleur.com/2020/09/29/worlds-most-unusual-languages/