The standout sight on Atiu. Anatakitaki — "the cave of three hearts" — is a multi-chambered limestone cave reached after a 30-minute walk through the makatea forest. Inside, hundreds of kopeka swiftlets navigate the dark with audible echolocation clicks, nesting in clusters on the cave roof.
The standard tour with Marshall Humphreys (Atiu Tours) or another local guide takes about three hours total and includes a swim in the cool freshwater pool at the back of the cave. The makatea walk on the way in is half the appeal — sharp, fossilised coral underfoot, dense rainforest overhead. Bring sturdy shoes and a torch.