In the town of Aquismón , in the Mexican state of San Luis Potosí, there is a wonder of nature, a natural abyss . The Sótano de las Golondrinas. This place is a cave of karst origin. This unusual formation has been created from the erosion of water on a fault, which has the characteristic of having an external opening that is narrower than its interior, which makes it have a conical shape. This upper opening has a diameter of about 60 meters, and is at ground level. However, the bottom reaches the maximum opening of 300 meters. Its depth is approximately 512 meters .
With these characteristics, the place is used by many birds as a natural refuge . But contrary to what their name suggests, these birds are not actually swallows. They are actually swifts . Some birds very similar to swallows, hence the confusion. It is a cave where you can also find a species of parrots known locally as “cave parrots”.
Until not long ago, the Sótano de las Golondrinas has been considered the largest cave in the world with its 512 meters deep, of which 376 are in free fall . Today many consider it as the most beautiful cavern or vertical basement on the planet.
The descent into this natural abyss, where the Eiffel Tower would be perfectly vertical, begins at dawn and you can see the spectacle of the flight of thousands of swifts and parrots that fly with incredible mathematical precision in a spiral. Currently this spectacular place is considered a Biosphere Reserve by the Mexican government.