Rapids create what we call as whitewater. And this formation is best-suited for river rafting!
Here in the Philippines, here are the top 5 rapids that I have seen.
1. Davao River
Related link - http://junvillegas.blogspot.com/2012/11/white-river-rafting-in-davao.html
2. Chico River
Related link - http://junvillegas.blogspot.com/2013/03/passing-in-kalinga.html
3. Cagayan De Oro River
Related link - http://junvillegas.blogspot.com/2013/03/white-water-rafting-in-cagayan-de-oro.html
4. Lulugayan Falls and Rapids, Calbiga, Samar
Related link - http://junvillegas.blogspot.com/2013/03/eastern-visayas-tour.html
5. Governor Rapids, Quirino
Related link - http://junvillegas.blogspot.com/2013/03/amazing-quirino.html