The Twelve Apostles, Port Campbell National Park, Australia, is one of the most spectacular stretches of coastline in Australia and the world. The Twelve Apostles have been created by constant erosion of the limestone cliffs of the mainland that began 10–20 million years ago. The stormy Southern Ocean and blasting winds gradually eroded the softer limestone, forming caves in the cliffs. Up to now, there are only seven left, when one of the eight remaining apostles collapsed into the sea.