Sinkhole divers. Some of the most spectacular are the Zacatón cenote in Mexico (the world's deepest water-filled sinkhole), the Boesmansgat sinkhole in South Africa, Sarisariñama tepuy in Venezuela, the Sótano del Barro in Mexico, and in the town of Mount Gambier, South Australia. Sinkholes that form in coral reefs and islands that collapse to enormous depths are known as blue holes and often become popular diving spots. Large and visually unusual sinkholes have been well-known to local people since ancient times. Nowadays sinkholes are grouped and named in site-specific or generic names. Some examples of such names are listed below. The
Cave Without a Name human contact with the cave began only in the early 20th century, when a small farm animal became trapped in the small external opening of the cave, known as a sinkhole. The cave went largely unnoticed again until the 1920s during the era of Prohibition when a small moonshine distillery was installed in the uppermost cavern. It again fell into obscurity until three local farm children rediscovered the sinkhole in 1935. These children are believed to be the first who actually entered the main chambers of the cave. After the rediscovery, Jim Horn, the original owner of the property decided