Silbo Gomero
Silbo Gomero (Spanish: silbo gomero [ˈsilβo ɣoˈmeɾo], "Gomeran whistle"), also known as el silbo ("the whistle"), is a whistled register of Spanish that is used by inhabitants of La Gomera, in the Canary Islands. It was historically used to communicate across the deep ravines and narrow valleys that radiate through the island and enabled messages to be exchanged over a distance of up to five kilometres.