Hierve el Agua is a geological formation that looks like petrified waterfalls. For thousands of years, mineral water flowed from rocks 50 to 90 meters high, precipitating calcium carbonate and forming incredible white stalactites that look like waterfalls. The smaller waterfall called Cascada Chica has several smaller natural and two bigger artificial swimming pools. One of the bigger pools is next to the edge of the cliff, so it is especially preferred by visitors who like the view from above while swimming.