The sands in Kazakhstan's Altyn-Emel national park play their own eerie music.
A tourist stands at the edge of the singing sand in Altyn-Emel national park in the Almaty region of Kazakhstan on May 12, 2016.
Locals call them the "singing sands" because they emit a low, musical sound. Scientists haven't figured out all the details of how they produce such synchronized notes, but they do have some idea of what's going on.
Here's what they have found out so far: