Hierve el Agua is a water spring, though it´s not hot as it´s name might make you think! Hierve el Agua literally means the water boils. This is a mountain with petrified waterfalls, one of only two in the world. Hierve el Agua is the result of thousands of years of calcium carbonate deposits. This heavily carbonated-calcified water “boils” to the surface because of hydraulic pressure. Along with swimming and appreciating the marvelous landscape, there is a great hiking loop that takes you around the waterfalls, revealing amazing rock formations.