Company Raft Trip Liability

[eggertr]

An Idaho company I work for sponsors a whitewater raft trip and barbecue every year. The barbecue is pot-luck but the company usually bears most of the cost of raft rentals. We know that the owner is personally liable for the barbecue since it is on his private property, but my question: does the company bear any liability for accidents or injuries sustained on the rafting part of the trip, which occurs on a navigable public waterway? The trip is not a required function and workers are off the clock. We were wondering if it would be necessary or even wise to have participants sign waivers.

Thanks for any help anyone can give.What is the name of your state (only U.S. law)?