There are a great number of white water programs to chose from, with ground transportation from San Jose, and professional bilingual tour operators and guides.
Comfort is met with quality meals, and roomy tents and thick pads for sleeping on overnights trips.
And unlike most of the other places you can visit, Costa Rica regulates its tourism industry making it very trustful because of it is held to strict standards. On the different places you can visit is always the same, there the sense of isolation is complete. Everything is as silent as a graveyard, except for the chattering monkeys and birds. With luck you may see small caiman in pools and shallows at lower elevations. Trips on the Reventazon, Pacuare, and Corobici are offered year-round, although in dry season the latter two rivers can be barely runable.