The inhabitants of which island can communicate using a whistling language?

Silbo Gomero is a whistled language used by the people of La Gomera. The island is the second smallest of the Canary Islands and roughly circular in shape and around 14 miles in diameter. It being a volcanic island it is very mountainous with peaks almost 5,000 feet high.The heights and ravines meant even shouting could not convey messages over long distances, whereas whistles can travel over 2 miles. The language has been documented since Roman times and developed by the Guanches who were the islands original inhabitants. During the 16th century the language was adopted by Spanish settlers and survived the assimilation of the Guanches.

With the advancements in roadways and communications the need for the language diminished. It is now used mainly by the inhabitants of the hills and ravines where even communication by phone is hit and miss.

With Silbo Gomero in danger of dying out in 1999 the government made the language together with Spanish compulsory for all school students. UNESCO also recognised the language as a Masterpiece of the Oral and Intangible Heritage of Humanity back in 2009.