| Knight Island | |
| Image Alt: | Aerial image of an island. |
| Pushpin Map: | United States San Francisco Bay Area#USA California#USA |
| Coordinates: | 38.1358°N -122.2994°W |
| Location: | Northern California |
| Waterbody: | Napa River |
| Area Sqft: | or |
| Area Acre: | --> |
| Length Ft: | --> |
| Width Ft: | --> |
| Coastline Ft: | --> |
| Elevation Ft: | 3 |
| Country: | United States |
| Country Admin Divisions Title: | State |
| Country Admin Divisions Title 1: | County |
| Country Admin Divisions 1: | Solano |
Knight Island is a mostly-submerged island in the Napa River, upstream of San Pablo Bay (an embayment of San Francisco Bay). It is in Solano County, California, and managed as part of the Napa-Sonoma Marshes Wildlife Area. Its coordinates are 38.1358°N -122.2994°W, and the United States Geological Survey measured its elevation as in 1981.