The Twelve Apostles is a collection of limestone stacks off the shore of the Port Campbell National Park, by the Great Ocean Road in Victoria, Australia. Their proximity to one another has made the site a popular tourist attraction.
The apostles were formed by erosion: the harsh and extreme weather conditions from the Southern Ocean gradually eroded the soft limestone to form caves in the cliffs, which then became arches, which in turn collapsed; leaving rock stacks up to 45 metres high. Now because of this erosion there are less then ten remaining.