I have traveled a number of time inside the Yellowstone caldera. Sitting on a rock trying to comprehend how something that large is a giant volcanic opening.., and if it blew., holy $hit.
Very cool place to visit. Not volcanic related but a sequence I'll never forget. I have motorcycled through Yellowstone from every entrance/exit.
One memorable early motorcycle visit in late May a herd of Bison were sauntering along the road just ahead of our group of 5 motorcycles. As we approached the herd of 25 Bison we slowed and they started to trot and then run ahead of us and off the road maybe 50 feet. We slowed to their pace of 10-15 mph? Well in another 300 or 400 yards the tree line started to pinch closer into the road and the Bison shifted closer., and soon you could see the fog from their breath and hear them snorting. They lope from side to side as they run and started jostling into a thinner line and they were maybe 10-15 feet off the road.
All at once we individually realized it was time to hit the gas and not have one of those critters bolt onto the road with us. Their eyes were wide and their noses running.