Here's a fascinating video on the Silbo Gomero, or whistled tongue of the island of Gomera in the Canary Islands of Spain. Today, it's essentially used as an encoding of Spanish that can be carried for long distances - more analogous to Leetspeak (73h 1337n3553 5p34|<5g3) and Braille than an independent language, but still linguistically very interesting.
Assuming I already speak Spanish well enough, are there any resources that specifically teach the whistled tongue? The video does mention that it is now being taught in schools, so a pedagogy must exist, but it is unclear if it is still something that you have to learn from another speaker (whistler?) or whether or not you can pick it up from books or videos.