The Cascade River is a river of the South Island

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

 of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

. It flows north for 30 kilometres from its source in Mount Aspiring National Park

Mount Aspiring National Park

Mount Aspiring National Park is located in the Southern Alps of the South Island of New Zealand, north of Fiordland National Park, and between Otago and south Westland. The park forms part of the Te Wahipounamu World Heritage site.-Geography:...

 in the Southern Alps

Southern Alps

The Southern Alps is a mountain range extending along much of the length of New Zealand's South Island, reaching its greatest elevations near the island's western side...

, forming a deep valley between the Olivine Range and Red Hills Range. From the end of this valley it turns west to cross a low-lying swampy floodplain

Floodplain

A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...

 before entering the Tasman Sea

Tasman Sea

The Tasman Sea is the large body of water between Australia and New Zealand, approximately across. It extends 2,800 km from north to south. It is a south-western segment of the South Pacific Ocean. The sea was named after the Dutch explorer Abel Janszoon Tasman, the first recorded European...

 close to Cascade Point, a headland halfway between Big Bay

Big Bay, New Zealand

Big Bay is a deep indentation in the southwestern coast of New Zealand's South Island. It is located 40 kilometres north of Milford Sound. The bay is eight kilometres in width, and extends eight kilometres into the South Island, making an almost square indentation in the island's coastline. It is...

 and Jackson Bay

Jackson Bay

Jackson Bay is a gently curving bay 24 kilometers wide, located on the West Coast of New Zealand's South Island. It faces the Tasman Sea to the north, and is backed by the Southern Alps...

.