Some unknown, but assuredly important pool. The Yellowstone experience is not just the sights, you know, it is the people. Somewhere around here, we met up with a family with at least 5 kids - everyone of them vying for the attention of the parents. "Mom! Mom! Look, there is a fish in there! Mom! Mom!" and "Dad! Dad! Can I swim in there? Can I? Dad! Dad! Can I?"