| Shag River | |
| Pushpin Map: | New Zealand Fiordland#New Zealand South Island#New Zealand |
| Pushpin Map Size: | 270px |
| Pushpin Map Caption: | Mouth of the Shag River |
| Source1 Coordinates: | -45.644°N 166.6054°W |
| Mouth Location: | Goose Cove |
| Mouth Elevation: | 0m (00feet) |
| Mouth Coordinates: | -45.6772°N 166.5532°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Progression: | Shag River → Goose Cove → Tamatea / Dusky Sound → Tasman Sea |
Shag River is a river on Resolution Island in Fiordland, New Zealand. It rises north west of Mount Roa and flows south into the Taumoana (Five Fingers Peninsula) Marine Reserve, part of Tamatea / Dusky Sound.