As we advanced upstream, the canyon walls got higher and higher. At some point, we were craning our necks to look at canyons walls 1000 feet above us.
I booked our boat tour with Wyoming Eco tours. They run from May to September. The tour is about 2 hours. They run one at 10 AM, one at 2 PM, and also a sunset cruise. They offer charters for large groups, as well.