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The Cave of Swallows, also called Cave of the Swallows (Spanish: Sótano de las Golondrinas), is an enormous pit cave situated in San Luis PotosÃÂ, Mexico. The entrance lies along a sloped section of karst, is elliptical in shape, and measures approximately 160 by 205 feet The entrance is undercut around its entire perimeter, and the pit opens up to a room that measures approximately 995 by 440 feet The low point of the entrance provides a 1094 feet (333 m) freefall drop to the bottom of the cave while the high point provides a 1220 feet (372 m) freefall drop. These measures make it the largest cave shaft in the world, second deepest pit in Mexico and the 11th deepest in the world.