Morning Glory Pool was a favorite destination for early visitors. It was named in the 1880s for its remarkable likeness to its namesake flower.

This blue pool soon became victim to vandalism. Over the years people have thrown in thousands of pounds of coins, trash, rocks, and logs into the pool. Much of this debris became embedded in the sides and vent of the spring, which reduced the water circulation and thus the water temperature. Vandalism has decreased, but remains a problem.

Natural changes may be cooling the water, too. Cooler temperatures allow orange- and yellow-colored bacteria to thrive.

Morning Glory Pool has an average temperate of 159.3°F (70.7°C).