Virtually every part of New Zealand has caves, but the best known caving areas are Waitomo, in the Waikato region of the North Island, and north-west Nelson and northern Westland, in the South Island.
Most New Zealand caves are limestone caves, or its metamorphic variety marble. There are also some lava caves, mainly around Auckland.
Waitomo Caves, in the heart of the King Country (Te Rohe Potae) and nestled in the greater Waikato region of the central North Island, offer New Zealand's most accessible caving network.
The vast Waitomo network is formed of hundreds of caves - more than 400 have been identified so far - and famed for many natural wonders, including spectacular limestone formations and some of the world's best glow worm displays.
Tourism opportunities include boat tours to view the glow worms among stalactites and stalagmites, and guided eco-adventures walking, abseiling and climbing in the caves or black water rafting a subterranean waterway.
In north-west Nelson, alpine caves are found at Takaka Hill, Mt Arthur, and Mt Owen, up to 1700m above sea level.
These three marble mountains contain all of New Zealand's deepest caves, as well as the three longest - the Bulmer, Ellis Basin system (28km / 17.39 miles), and Nettlebed both at Mount Arthur.
Nettlebed, at Mt Arthur, is New Zealand's deepest cave surveyed at 889m / 2916ft. It is also the third longest at 24.25km / 15 miles.
Bulmer Cavern, at Mt Owen, is New Zealand's longest cave. It is 39.9km / 24.8 miles - of which 400m is as yet unsurveyed.
Karamea, in Westland, features the 13km / 8.07 miles Honeycomb Hill Cave. Honeycomb Hill has 70 entrances, plus New Zealand's largest limestone arches.
Tucked away in a corner of Kahurangi National Park, the Oparara valley has three spectacular limestone arches over the river and a complex 15km cave system that help make this an area of national and international significance.
The Oparara caves are renowned for the discovery of the largest collection of subfossil bird bones found in New Zealand.
Over 50 species - dating from 20,000 years ago, many now extinct - have been discovered including moa, giant New Zealand eagle, giant flightless goose and rare native birds such as takahe and kakapo.
Rikoriko cave - Northland
Rikoriko cave, the world’s largest sea cave, is located in the Poor Knights Islands, in the Northland region of New Zealand.
Dive Tutukaka runs eco-tours exploring the caves, arches, marine and bird life unique to the Poor Knights marine reserve.
Rikoriko cave is renowned for its acoustics. Live concerts - including Kiwi artist Neil Finn - have performed in the natural auditorium.
Hiking in Kahurangi Park