Complex sentence: At the end of the canyon the Wind River widens out in what is called the Wedding of the Waters, where it becomes the Bighorn River and enters the Bighorn Basin, where it continues northward, passing through Thermopolis, Worland, and Basin.
Split into simpler sentences: At the end of the canyon the Wind River widens out in an area called the "Wedding of the Waters" where it becomes the Bighorn River and enters the Bighorn Basin. The Bighorn continues northward, passing through Thermopolis, Worland, and Basin.