| Duncan River | |
| Pushpin Map: | New Zealand Fiordland#New Zealand South Island#New Zealand |
| Pushpin Map Size: | 270px |
| Pushpin Map Caption: | Mouth of the Duncan River |
| Source1 Coordinates: | -44.2561°N 168.225°W |
| Mouth Location: | Gorge River |
| Mouth Coordinates: | -44.2451°N 168.0975°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Subdivision Type2: | Region |
| Subdivision Name2: | West Coast Region |
| Subdivision Type3: | District |
| Subdivision Name3: | Westland |
The Duncan River is a river in the West Coast Region of New Zealand. It arises in the Red Hills Range and flows north-east to the Gorge River, which flows west into the Tasman Sea.[1]