The Sudwala Caves near Nelspruit in Mpumalanga (South Africa) are geologically speaking the oldest known caves in the world. Hour-long tours through the caves are conducted daily. A five-hour long Crystal Tour to the bowls of the earth is offered once a month for the more adventurous.

The Caves consist of dripstone formations and twisted tunnels with fanciful names such as: Screaming Monster, Devil's Pulpit, Lot's Wife, the Fairy Glen, Weeping Madonna, Samson's Pillar, Lover's Lane, Whispering Tunnel, and the Wolf. One particularly vivid dripstone, the Space Rocket, is 11m high. The biggest cavern in the caves is the P.R. Owen Hall, which is 70 metres wide (±210 feet) and 37 metres high (±111 feet). Sudwala is a Karst Cave, i.e. a cave formed by the force of water containing carbon dioxide (CO2), which is able to dissolve limestone.

Historical events linked to the Sudwala Caves include:
- In the early 1800's the king of the Swazis, Sobhuza, found shelter in the caves while hiding from the militant Ndwandwe Zulu tribe.
- The author of "She" and "King Solomon's Mines", Rider Haggard, visited Sudwala in the late 1800's.
- During the Anglo-Boer War (1899-1902) the Boers stored ammunition for their heavy 94-pounder "Long Tom" artillery guns in the Caves.
- In 1970 Ivan Rebroff tested the acoustics of the P.R. Owen Hall and concluded that it was "...at least equal if not superior to those of any concert hall or opera house in Europe".

(Source: some info adapted from www.showcaves.com - see link below).

(Also see: Cango Caves)