The annual Robben Island Triathlon adds a 14 km run this year to the swim-bike-run formula of the competition.
The triathlon includes a harbour swim and then bicycling and running past many of the island's key tourists sites, including the hard labour lime pits, the lighthouse and the world war two cannon. The competition comes in two versions; the easier 4 m swim: 14 km cycle: 4 km run and the tougher 8:28:8.
This year corporate packages have been introduced for the first time and participants can also book over-night accommodation and a meal in the prison itself.
Robben Island is now a World Heritage Site but it has a history as a leper colony, quarantine centre and most recently as a maximum security political prison from 1961 until 1991 under the apartheid regime. Its most famous prisoner was Nelson Mandela who was interned there for 18 years.
It is also a site of Muslim pilgrimage to the Moturu Kramat, a shrine built in 1969 to commemorate Sayed Abdurahman Moturu, one of Cape Town's first imans who was exiled to the island and died there in 1754.