Welcome Mountaindivegirl !
I went to your area for the solar eclipse. When I saw Yellowstone Lake, I instantly wondered if it is 'diveable' and what is in it. And also figured it must be 'too cold' for me (since I have never dove anywhere north of south Florida :-) At least we can assume there are no alligators in that lake.
I spent a day at the Cody Museum. If I had time to spend a week there, I would have.