Morning Glory Pool is one of the most beautiful pools in Yellowstone National Park. Morning Glory earned its name in the 1880's due to its deep blue coloration and likeness to the Morning Glory flower. Over the years visitors tossed tons of coins, trash, sticks and rocks into the pool, causing its vent to clog and the flow of water to decrease. This prompted the temperature in the pool to lessen, causing the pool's deep blue color to fade and allowing the red and yellow algae that formerly only survived at the fringe of the pool to grow toward the center. Morning Glory Pool has on rare occasions been known to erupt as a geyser, leading to some failed efforts in the past to deliberately induce eruptions in an effort to clear the pool's vent.