Ruakuri Cave has an impressive 15m-high spiral staircase, bypassing a Māori burial site at the cave entrance. Tours lead through 1.6km of the 7.5km system, taking in caverns with glowworms, subterranean streams and waterfalls, and intricate limestone structures. Visitors have described it as spiritual – some claim it’s haunted – and it’s customary to wash your hands when leaving to remove the tapu (taboo). Book tours at the visitor centre, or at the departure point, the Legendary Black Water Rafting Company.