The ancient island of Mangaia is thought to be the oldest island in the South Pacific, and it's a place where you can certainly feel the centuries stretching back. Vast circular towers of makatea (raised, fossilised coral reef) ring the island's fertile central valleys, in some places dropping down in sheer 60m cliffs, and there are several scenic lookouts where you can admire uninterrupted views across to the highest peak on the island, Rangimotia. It's a proud and mysterious island, renowned for its unique culture and sense of independence, and there are many ancient marae (ancient meeting grounds) to discover, as well as some of the finest Missionary-era churches in the Cook Islands. But like the other islands of the Southern Group, Mangaia is most famous for its dramatic cave systems, especially the massive burial chamber of Te Rua Rere and the labyrinthine Tuatini Caves. It's also rumoured to be a haunted island - the spirits of ancient ancestors are believed to walk aboard on the island once the sun sets, and many locals won't venture into the murky makatea after dark.