||The major island groups are 'Eua, Ha'apai, , Tongatapu and Vava'u. Tonga's high volcanic and low coral forms give the islands a unique character. Some volcanoes are still active and Falcon Island in the Vava'u group is a submerged volcano that erupts periodically, its lava and ash rising above sea level forming a visible island which disappears when the eruption is over. Nuku'alofa the capital city is located on Tongatapu Island and has a reef-protected harbour lined with palms. Whilst here you should visit the Royal Palace and also the burial chambers. The island is flat with a large lagoon, but no running streams, and many surrounding smaller islands. 'Eua Island is hilly and forested with high cliffs and beautiful beaches. Most visitors would come here as they are close to Nuku’alofa and have the finest beaches in the kingdom. The Ha'apai Islands, a curving archipelago 160 kilometres north of Tongatapu, have excellent beaches. Tofua, the largest island in the group, is an active volcano with a hot steaming lake in its crater. The Vava'u Islands, 90 kilometres north of Ha'apai, are hilly, densely wooded and interspersed with a maze of narrow channels. They are known for their stalagmite-filled caves.