Here is a good list of locations you can try checking out 1.
Futaleufu River White Water Rafting, Chile
2. Cherry Creek/Upper Tuolumne White Water Rafting, California,
U.S.A
3. Zambezi River White Water Rafting, Zimbabwe.
4. Great Bend of the Yangtze River White Water Rafting,
China
5. Río Upano White Water Rafting, Ecuador.
6. Magpie River White Water Rafting, Quebec, Canada
7. Karnali River White Water Rafting, Nepal
8. Gauley River White Water Rafting, West Virginia, U.S.A
9. Middle Fork of the Salmon White Water Rafting, Idaho,
U.S.A.
10. Victoria Nile White Water Rafting, Uganda