| Unterwarnow | |
| Location: | Baltic Sea |
| Coords: | 54.1041°N 12.1041°W |
| Rivers: | Warnow |
| Oceans: | Atlantic Ocean |
| Countries: | Germany |
| Pushpin Map: | Mecklenburg-Vorpommern |
| Max-Depth: | 13m (43feet) |
| Salinity: | ~10‰ |
| Cities: | Rostock |
Unterwarnow is the estuary of the Warnow River in Mecklenburg-Vorpommern, northern Germany. Connected with the Baltic Sea in Warnemünde. On the coasts of the estuary, the city of Rostock is located.