The seaward edge of Fiordland National Park is a series of fourteen massive knife cuts, carved by the glaciers during successive ice ages. Towering, snow-capped peaks reflect in the midnight blue fingers of ocean that reach into the park's thickly forested interior, where visitors can find trees that are more than 800 years old. For sheer drama, few places of earth can compete with this remarkable natural environment. In 1990 Fiordland was listed as a United Nations World Heritage site and given the name Te Wahipounamu - 'the place of greenstone', after the area's most treasured mineral resource. The remaining two thirds of Fiordland National Park are covered by virgin beech and podocarp forest. A 500 kilometre network of walking tracks allows visitors to explore the primeval world of mountain peaks, alpine lakes and moss-carpeted valleys. Three of New Zealand's 'Great Walks' can be found in the park. The most famous (and consequently most crowded) is the Milford Track, which takes five days to complete. The Kepler Track is a circular route that can be walked in four days and the Routeburn, which crosses into Mount Aspiring National Park, generally takes three days. There are many other less famous, but just as spectacular, tracks to explore. Several of the fiords can be explored by sea kayak, as can lakes Te Anau and Manapouri. Diving in Fiordland provides a rare chance to see deepwater sea plants growing near the surface. Local residents include dolphins, fur seals and penguins.