This image of Yellowstone Lake, in the center of Yellowstone National Park, was taken by Landsat 7 on July 13, 1999. Bands 5 (1.65µm),4 (.825µm), and 2 (.565µm) were used for red, green, and blue, respectively. Water appears blue/black, snow light blue, mature forest red/green, young forest pink, and grass and fields appear light green.
Southwest of the lake is young forest that is growing in the wake of the widespread fires of 1988.
For more information, see:
Landsat 7 Fact Sheet
Image by Rich Irish, NASA GSFC