| Viskan | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Sweden |
| Subdivision Type3: | Counties |
| Subdivision Name3: | Västra Götaland County, Halland County |
| Subdivision Type5: | City |
| Subdivision Name5: | Borås |
| Length: | 140km (90miles)[1] |
| Discharge1 Avg: | 34m3/s |
| Source1: | Tolken |
| Source1 Location: | Ulricehamn Municipality, Västra Götaland County, Sweden |
| Source1 Coordinates: | 57.7917°N 13.25°W |
| Source1 Elevation: | 226m (741feet)[2] |
| Mouth: | Klosterfjorden, Kattegatt |
| Mouth Location: | Varberg Municipality, Halland County, Sweden |
| Mouth Coordinates: | 57.225°N 12.2056°W |
| Mouth Elevation: | 0m (00feet) |
| Basin Size: | 2202.1km2[3] |
| Tributaries Left: | Häggån, Slottsån |
| Tributaries Right: | Munkån, Surteån |
Viskan is a river in the south west of Sweden. It is about 140 kilometers long. It starts in the lake Tolken outside Ulricehamn and has its outlet in the Kattegatt. It runs through Borås.