| Douglas River | |
| Name Other: | Twain River |
| Name Etymology: | Named after Charlie Douglas, an explorer of the region |
| Pushpin Map: | New Zealand South Island#New Zealand |
| Pushpin Map Size: | 270px |
| Pushpin Map Caption: | Mouth of the Douglas River |
| Source1: | Douglas Glacier |
| Source1 Coordinates: | -43.6965°N 169.9377°W |
| Source1 Elevation: | 975m (3,199feet) |
| Mouth: | Karangarua River |
| Mouth Location: | Cassel Flat |
| Mouth Elevation: | 178m (584feet) |
| Mouth Coordinates: | -43.6675°N 169.8301°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Subdivision Type2: | Region |
| Subdivision Name2: | West Coast |
| Subdivision Type3: | District |
| Subdivision Name3: | Westland |
| Length: | 18km (11miles) |
| Progression: | Douglas Glacier → Douglas River → Karangarua River → Tasman Sea |
| River System: | Karangarua River |
The Douglas River, formerly known as the Twain,[1] is a river of the West Coast of New Zealand's South Island. Its source is high in the Southern Alps / Kā Tiritiri o te Moana, 5km (03miles) south of Mount Sefton, and its upper reaches are fed by water from the Douglas Glacier. It flows west for, joined by runoff from the Horace Walker Glacier, before joining the waters of the Karangarua River. The Douglas River's entire course is within Westland Tai Poutini National Park.[2] The river and glacier are named after Charles Edward Douglas, a 19th-century explorer and mountaineer.[3]
The New Zealand Department of Conservation maintains a backcountry hut at the junction of the Douglas and Horace Walker rivers.[4]