The Marimán rapids are in the Trancura river and you can visit them, they are about 14 kilometers from Pucón. (lat=-39.299725,lon=-71.845545)
A entrance fee of $1.000 pesos is charged and there is short trail along the river to see the rapids from varios angles.
Entrance to the rapids
First rapids seen from the trail
The trail is easy as it has been paved with wood
The second and most powerfull rapids
The Trancura river as seen from the end of the trail