| Seefelder Aach | |
| Name Other: | Salemer Aach, Linzer Aach |
| Source1 Location: | Between Alberweiler and Herdwangen in Herdwangen-Schönach |
| Mouth Coordinates: | 47.7331°N 9.2264°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Germany |
| Subdivision Type2: | State |
| Subdivision Name2: | Baden-Württemberg |
| Subdivision Type3: | Region |
| Subdivision Name3: | Tübingen |
| Length: | 54.7km (34miles) |
| Source1 Elevation: | 670m (2,200feet) |
| Mouth Elevation: | 395m (1,296feet) |
| Basin Size: | 279km2 |
| Tributaries Left: | Furtbach, Erlengraben, Aubach, Deggenhauser Aach, Gießbach |
| Tributaries Right: | Herdenbach, Wäschbach, Torpenbach, Nellenflurb |
The Seefelder Aach is a river in the districts of Sigmaringen and Bodenseekreis, Tübingen region, southern Baden-Württemberg, Germany. It is approximately 55 kilometres long and flows into Lake Constance. It has a catchment area of 279 km2 and is part of the Rhine river system. It starts as Salemer Aach and becomes the Seefelder Aach after the conjunction with the Deggenhauser Aach, further down from Salem. The upper part – near Aach-Linz – it is also colloquially called Linzer Aach or Hintere Aach.[1] [2]