Be in this place this summer and even though not heard the real one personal it is quite famous

https://en.m.wikipedia.org/wiki/Silbo_Gomero

Here's a Turkish whistled language in action: https://youtu.be/bQf38Ybo1IY?t=1m40s

The Tleilaxu use a whistled language in the Dune sequels to control their gholas.

http://dune.wikia.com/wiki/Whistling_language

I came across an article on a disappearing Greek whistled language earlier this year:

http://www.bbc.com/travel/story/20170731-greeces-disappearin...

Related: Solresol, a conlang built on music

https://en.m.wikipedia.org/wiki/Solresol

First thing comes to mind is Yondu, from 'Guardians of the Galaxies'.

Movies borrowed inspirations from this, maybe?

Maybe Toki Pona could be adapted to boatswain whistle?