What is the largest cave shaft in the world?

The largest known cave shaft in the world is the Cave of Swallows, also called Sótano de las Golondrinas. It is an open-air pit cave near Aquismón in Mexico's San Luis Potosí state, where the entrance opens into a vast vertical chamber.

The cave's floor lies roughly 333 to 376 metres below the higher side of its opening, making the drop deep enough for a skyscraper-sized free fall. Its elliptical entrance is about 135 metres long and 305 metres wide, creating an extraordinary shaft rather than a conventional winding cave passage.

The site was recorded by outsiders in 1966, although local communities knew the area earlier. The Spanish name means “Basement of the Swallows,” referring to the birds that fly in and out of the shaft. The birds are more accurately swiftlets and parrots, not true swallows.

Son Doong Cave, Carlsbad Caverns, and Mammoth Cave are also celebrated underground wonders, but they are known for different records involving volume, passages, or length. The Cave of Swallows is the specific answer for the world's largest cave shaft.