This can be done in half a day if time doesn't extend to the Colca Canyon as it is only a 45 minute drive. The rapids are grades III and IV and the views of El Misti as you go along are spetactular. We had local guides who were great about making sure everyone felt safe (even the nervous First Timers) and all equipment was provided. It a great contrast to the sightseeing in Arequipa.
There are lots of places offering trips, we went through a place just on Jerusalen road.
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