The Waitomo Glowworm Caves is a limestone cave group in the western mountains of New Zealand's North Island; it is a famous New Zealand scenic spot. In the Maori language, Waitomo means "surrounded by green waters." The caves consists mainly of three distinct caves, the Waitomo Glowworm Cave, the Ruakuri Cave and the Aranui Cave. The Waitomo Glowworm Cave is a stalactite cave. The Cathedral Cavern inside the cave is especially well known for its echo. The Ruakuri Cave is an underground cave where visitors can hear the musical sounds of an underground waterfall. The entrance to the Aranui Cave is also the visitor center. The membrane structured arch here is very magnificent.