 The submarine volcano Karua, one of the most active volcanoes of Vanuatu, is near the northern rim of Kuwae Caldera.Tongoa and Epi islands once formed part of a larger island called Kuwae.Local folklore tells of a cataclysmic eruption that split this island into two smaller islands with an oval 12 x 6 km caldera in between (but the story tells of an eruption south of Tongoa).