Mangaia has many spectacular caves, including Te Rua Rere, a huge burial cave that has crystalline stalagmites and stalactites, and some ancient human skeletons. Other caverns worth exploring include the multilevel Tuatini Cave and the long, maze-like Toru a Puru Cave.
Some of the finest old CICCs in the Cooks are on Mangaia. Tamarua CICC is especially beautiful, and still has its original roof beams, woodcarved interiors and sennit-rope binding. The interiors of the Oneroa and IviruaCICCs were once even more impressive, but were sadly mostly removed in the 1980s.
The island also has 24 pre-missionary marae, but you’ll need a guide to find them since they have been mostly overtaken by bush.