We enjoyed a wonderful private full day tour with Derek who was knowledgeable, friendly, and so great! He is so informative about all of the geo-thermal features, and was very flexible with what we wanted to focus on. We did some hiking, got to see a big black bear, bison, antelope, an osprey rookery, and learned all about the park. Picking us up right from our lodging -providing a lovely picnic lunch-showing us nests through his scope-provided a great day for our family of 4 adults. We highly recommend Derek and this tour -especially for first timers to the park!