| Koetoi River | |
| Name Other: | 声問川 |
| Subdivision Type1: | Country |
| Subdivision Name1: | Japan |
| Subdivision Type2: | State |
| Subdivision Name2: | Hokkaidō |
| Subdivision Type3: | Region |
| Subdivision Name3: | Sōya |
| Subdivision Type4: | District |
| Subdivision Name4: | Wakkanai |
| Length: | 41.9km (26miles) |
| Source1: | Mount Etanpakku |
| Source1 Location: | Wakkanai, Hokkaidō, Japan |
| Source1 Coordinates: | 45.2306°N 142.0133°W |
| Source1 Elevation: | 313m (1,027feet) |
| Mouth: | Sōya Bay |
| Mouth Location: | Wakkanai, Hokkaidō, Japan |
| Mouth Coordinates: | 45.4075°N 141.7556°W |
| Mouth Elevation: | 0m (00feet) |
| Basin Size: | 294.8km2 |
is a river in Hokkaidō, Japan.[1]