If you are looking for an interesting side adventure, maybe try a trip to soak in the Boiling River. Located between Mammoth and Gardiner. There is a short hike of about .6 miles from the parking area to where you venture into the soaking area. The Boiling River merges with the Gardiner River creating a comfortable soaking area near the North East entrance to Yellowstone. In the Spring the Gardiner River flows are high with snowmelt, this is more of a mid to late Summer activity.
“Many of Yellowstone National Park’s thermally-influenced waters contain organisms that are known to cause serious skin rashes, infections, and/or primary amoebic meningitis, which can be quickly fatal. The thermal waters of Boiling River have been shown to support the organisms that can cause Primary amoebic meningoenchephalitis and Legionnaire’s disease. Avoid submerging your head and inhalation of thermal steam. If you have any signs of symptoms of irritation or disease seek medical help immediately. Swim at your own risk.” Hundreds of people swim in Boiling River each day. While the dangers are minimal, precautions should be taken. As a precaution it is recommended that you do not put your head below the surface.