New Zealand's Deepest Cave video

Exploring the Nettlebed Caves. They are located in the Mt Arthur tablelands behind Nelson, contain 26KM of tunnels, and are of 420 million year old marble. They contain many rare bird fossils and ancient pollen records and are pretty dangerous to navigate so they are not advertised to the public as a destination. So very high scientific value indeed. There is information on them on the NZSS website and the Canterbury Cavers website.