Milford Sound (Piopiotahi in Māori) is a fiord in the south west of New Zealand's South Island, within Fiordland National Park and the Te Wahipounamu World Heritage site. It has been judged the world's top travel destination in an international survey, and is acclaimed as New Zealand's most famous tourist destination. Rudyard Kipling had previously called it the eighth Wonder of the World.
Milford Sound is named after Milford Haven in Wales, while the Cleddau River which flows into the sound is also named for its Welsh namesake. The Māori named the sound Piopiotahi after the thrush-like piopio bird, now extinct. Piopiotahi means "a single piopio", harking back to the legend of Māui trying to win immortality for mankind - when Maui died in the attempt, a piopio was said to have flown here in mourning.
Milford Sound runs 15 kilometres inland from the Tasman Sea and is surrounded by sheer rock faces that rise 1,200 metres or more on either side. Among the peaks are The Elephant at 1,517 m (4,977 ft), said to resemble an elephant's head, and Lion Mountain, 1,302 m (4,271 ft), in the shape of a crouching lion. Lush rain forests cling precariously to these cliffs, while seals, penguins, and dolphins frequent the waters.
Accumulated rainwater can at times cause portions of the rain forest to lose their grip on the sheer cliff faces, resulting in tree avalanches into the sound. The regrowth of the rain forest after these avalanches can be seen in several locations along the sound.
Milford Sound was initially overlooked by European explorers, because its narrow entry did not appear to lead into such large interior bays. Sailing ship captains such as James Cook, who bypassed Milford Sound on his journeys for just this reason, also feared venturing too close to the steep mountainsides, afraid that wind conditions would prevent escape.
While Fiordland as such remained one of the least-explored areas of New Zealand up to the 20th century, Milford Sound's natural beauty soon attracted national and international renown, and led to the discovery of the McKinnon Pass in 1888, soon to become a part of the new Milford Track, an early walking tourism trail. In the same year, the low watershed saddle between the Hollyford River and the Cleddau River was discovered, where the Homer Tunnel was to be developed about sixty years later to provide road access.
Tramping (New Zealand English for hiking or backpacking), canoeing and some other water sports are also possible. A small number of companies also provides overnight boat trips. There is otherwise only limited accommodation at the sound, and only a very small percentage of tourists stay more than the day.
An underwater tourist observatory found in one of the bays of the sound provides viewing of black coral, usually only found in much deeper waters. A dark surface layer of fresh water, stained by tannins from the surrounding forest, allows the corals to grow close to the surface here.
By road, Milford Sound is 295 km from Queenstown and 279 km from Invercargill (about four hours drive), with most of the tour buses to the sound departing from Queenstown. Some tourists also arrive from the smaller tourism centre of Te Anau, 121 km away. There are also scenic flights by light aircraft and helicopter tours to and from Milford Sound Airport. The drive to Milford Sound itself passes through unspoiled mountain landscapes before entering the 1.2 km Homer Tunnel which emerges into rain-forest-carpeted canyons that descend to the sound. The winding mountain road, while of high standards, is very prone to avalanches and closures during the winter half of the year.
The long distance to the sound means that tourist operators from Queenstown all depart very early in the day, arriving back only late in the evening. This ensures that most tourists visit Milford Sound within a few hours around midday, leading to some congestion on the roads and at the tourist facilities during the main season. The peak-time demand is also the reason for the large number of tour boats active in the sound at much the same time.
Over the years, various options of short-cutting the distance to Milford Sound from Queenstown have been mooted, including a gondola route, a new tunnel from Queenstown, or a monorail from near Lake Wakatipu to Te Anau Downs. All would reduce the current round-trip duration (which has to travel via Te Anau), thus allowing tourism to be spread out over more of the day. While a gondola is considered to be out of the running after the DOC refused it for environmental reasons, the two other options are aiming to start consenting processes in 2007.
Milford Sound can also be reached on foot as the final destination of the several-day Milford Track.
On 8 February 2004 a spill of 13,000 litres of diesel fuel was discovered, resulting in a 2-kilometre oil spill which closed the sound for two days while intensive cleanup activities were completed. Apparently a hose was used to displace the fuel from the tanks of one of the tour vessels, and various government officials claimed it appeared to be an act of ecoterrorism motivated by rising numbers of tourists to the park, though more details did not become known. The spill has been removed and damage to the park's wildlife appears to have been minimal.