'Eua has several limestone cave systems, of which Ana Hoko (also known as Hopo Cave) is the most accessible. The cave system runs through the limestone interior of the island, with chambers large enough to walk through and a freshwater spring in the lower sections. Stalagmites and stalactites are well-developed in some passages, and the cave floor is soft with centuries of bat guano.
Access is best arranged through a local guesthouse, which can provide a guide with a torch. The cave systems are not signposted or formally managed, and getting lost in the limestone passages is a real possibility without a guide. Bring good footwear — the cave floors are uneven and often wet.