Keelung River
These naturally occurring potholes are of great interest to geologists, as they're quite uncommon. The best-known kettle holes in Taiwan are a mass of indents in the exposed bed of the Keelung River at the town of Nuannuan, near Keelung City, although part of their fame is surely due to their lying right beside a busy road. Keelung River near Nuannuan has a narrower river channel and thus faster flowing water and turbulents which results in the formation of potholes. Riverbed potholes normally take many hundreds years to form and it is an extremely important geological feature. The formation phenomena provokes wide research interests in fluid dynamics, landscape, geology, climate, hydrological and rock studies. Its rarity also serve as an invaluable educational resource for everybody.