There is no rafting available actually within the Park but you can access a white water rafting or kayaking trip from several of the gateway communities. Gardiner is a particularly good spot to get a rafting trip as you can access the Yellowstone River from here. There are several operators, we have had a wonderful time with the Yellowstone Raft Company

http://www.yellowstoneraft.com/

and have heard good reports of Montana Whitewater and Wild West Rafting.

If white water isn’t your thing several companies do scenic floats – as the name suggests these are nice peaceful trips along the river where you float along, often looking for wildlife.

If neither scenic or white water rafting is your thing, the companies mention above also do kayaking trips.

Jackson is another good centre for rafting with white water opportunities along the Snake River and scenic floats available in the Grand Teton National Park. The evening floats are a great way to see wildlife, especially beaver.