- Cape Arago, Coos County, Oregon, United States1
- Cape Lookout National Seashore, North Carolina, United States, (Area)1
- Cascade Range, Oregon, United States, (Hypsographic)1
- Central America, , (Area)1
- Chamela, Jalisco, Mexico, (Populated Place)1
- Champoeg, Oregon, United States, (Populated Place)1
- Chernobyl Exclusion Zone, Kyiv, Ukraine, (Administrative Boundary)1
- Chetco River Estuary, Oregon, United States, (Hydrographic)1
- China1
- City of Corvallis, Oregon, United States, (Administrative Boundary)1
- City of Unalaska, Alaska, United States1
- Clackamas, Oregon, United States, (Administrative Boundary)1
- Coachella Valley, California, United States, (Populated Place)1
- Colón, Colón, Panama, (Populated Place)1
- Congo Republic, , Congo Republic, (Administrative Boundary)1
- Coos Bay Estuary, Oregon, United States, (Hydrographic)1
- Coos Bay, Oregon, United States, (Hydrographic)1
- Coos, Oregon, United States, (Administrative Boundary)1
- Copper River Delta, Alaska, United States, (Area)1
- Coquille River Estuary, Oregon, United States, (Hydrographic)1