The first U.S. national park is famous for a reason—and not just because of Old Faithful , a collection of the world's most extraordinary geysers and hot springs or the Grand Canyon of the Yellowstone. It has unbelievable wildlife, stunning geographic formations and terrain ripe for exploration 365 days a year. I've been to the park five times and still feel I have just scratched the surface. You could spend a month in each area of the park and from a photographers perspective you have four seasons and early morning and evening light to challenge you.