| Swift Diamond River | |
| Pushpin Map: | New Hampshire#USA |
| Pushpin Map Size: | 275 px |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New Hampshire |
| Subdivision Type3: | County |
| Subdivision Name3: | Coos |
| Subdivision Type4: | Townships |
| Subdivision Name4: | Stewartstown, Dixville, Dix's Grant, Second College Grant |
| Length: | 17.8miles |
| Source1: | Dead Water Ridge |
| Source1 Location: | Coleman State Park |
| Source1 Coordinates: | 44.9517°N -71.3336°W |
| Source1 Elevation: | 2365feet |
| Mouth: | Dead Diamond River |
| Mouth Location: | Second College Grant |
| Mouth Coordinates: | 44.8819°N -71.0708°W |
| Mouth Elevation: | 1335feet |
| Tributaries Left: | Alder Brook, Roaring Brook, Fourmile Brook |
| Tributaries Right: | Nathan Pond Brook, Dixie Brook |
The Swift Diamond River is a 17.8adj=midNaNadj=mid[1] river in northern New Hampshire in the United States. It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed.
The Swift Diamond River rises in the town of Stewartstown, New Hampshire, atop Dead Water Ridge within Coleman State Park. The stream flows east into Little Diamond Pond, and then Diamond Pond. The river continues southeast and then east through mountainous and heavily forested terrain, where the chief land use is logging. The river passes through the townships of Dixville and Dix's Grant before joining the Dead Diamond River in the Dartmouth College Grant.