Contributor Postandfly created this spectacular drone video of one of the world's most unusual rock formations. The Hierve el Agua (the "water boils") is a a set of formations that look very much like streams of cascading water. Amazingly so, especially when viewed from an aerial perspective. The pheonenon is caused by streams of spring water that are over-saturated with the mineral calcium carbonate. They are located in the Mexican state of Oaxaca, in the southern region of the country.