One of the most extensive of these are the Cango Caves near the town of Oudtshoorn in the Western Cape, a series of limestone caves found in the foothills of the Swartberg mountains.

Here, visitors can opt for the standard heritage tour or the more extreme 90-minute adventure tour, during which they will be required to leopard crawl through tight spaces. Anyone who suffers from claustrophobia should not sign up.

The reward, however, is a sense of achievement and the chance to view unspoilt rock formations that are only accessible to the adventurous few. Some of these will have been formed over unimaginable lengths of time (it takes about 100 years for a half-inch or 1.2cm stalactite to form).

Other caves open to the public include the Sterkfontein Caves and Wonder Cave in the Cradle of Humankind (where visitors can also do an 18m abseil into the cave before going on a guided tour) and the Sudwala Caves and the Echo Caves in Mpumalanga.

However, these ‘show’ caves don’t really qualify when it comes to the more extreme sport of caving, a niche activity that requires a high degree of fitness and a level head.

Any clients wishing to get into more serious caving should be advised to locate a reputable operator who will take them on expeditions to areas not generally open to the public. One of these is Wild Caves Adventures based in the Cradle of Humankind heritage site close to Johannesburg. These operators, however, are few and far between.