A fjord is a long, narrow, deep inlet of the sea between high cliffs, as found in Norway and Iceland, typically formed by submergence of a glaciated valley. Milford Sound is a fjord formed by a process of glaciation over millions of years and is located in the south west of New Zealand's South Island. It is within Fiordland National Park, "Piopiotahi" (Milford Sound) Marine Reserve, and the "Te Wahipounamu" World Heritage site.

It runs 15 km inland from the Tasman Sea at Dale Point —the mouth of the fjord—and is surrounded by rock faces that rise 1,200 m (3,900 ft) on either side. Among the peaks are “The Elephant” at 1,517 m (4,977 ft), said to resemble an elephant's head, and “The Lion”, 1,302 m (4,272 ft), in the shape of a crouching lion. Milford Sound has two permanent waterfalls, "Lady Bowen Falls" and "Stirling Falls". Both are fed by rain water.

The fjord 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.

Described by Rudyard Kipling as the "8th wonder of the world", the cliffs rise vertically from the waters and waterfalls cascade downwards from as high as 1000 metres.

More Info: en.wikipedia.org