Milford Sound: Mitre Peak, the mountain at left, rises 1692 meters above the Sound.

Milford Sound (Piopiotahi) is located on the south west corner of the South Island of New Zealand. Although called Milford Sound it is more accurately classified as a fjord. Milford Sound is situated within the Fiordland National Park which is in turn part of the Te Wahipounamu World Heritage site.

Milford Sound runs 15 kilometres inland from the Tasman Sea and is surrounded by sheer rock faces that rise 1200 metres or more on either side. Lush rain forests cling precariously to these cliffs, while seals, penguins, and dolphins frequent the waters. The natural beauty of this landscape draws thousands of visitors each day. Tourists should be sure to bring umbrellas, however, as Milford Sound receives over seven meters of rain annually. Far from being a damper on a visit, though, each rainfall creates dozens of "temporary waterfalls" down the cliff faces, some reaching a thousand meters in length. Be careful, though: 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 is located about five hours' drive from Queenstown; many tour buses to the Sound depart from there, as well as much pricier helicopter tours. The drive itself passes through unspoiled mountain landscapes before entering the 1.2-kilometer Homer Tunnel which emerges into rain-forest carpeted canyons that descend to the sound.

Boat tours of the sound are offered by several companies, departing from the Milford Sound Visitors' Center. Hiking (tramping, in New Zealand English) and canoeing are also possible. An underwater observatory 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.

On 8 February 2004 a spill of 13,000 litres of diesel fuel was discovered, resulting in a 2 kilometer 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. Various government officials claimed it appeared to be an act of ecoterrorism motivated by rising numbers of tourists to the park. As of the time of this writing (February 19) no further information is known. The spill has been removed and damage to the park's wildlife appears to have been minimal.

Milford Sound is named for Milford Haven in Wales, and the Cleddau River which flows into it is similarly named for a Welsh namesake . The Maori name for the sound, Piopiotahi, means first native thrush.