Ice algae
Watermelon snow is snow that is reddish or pink in color, and that can have a smell similar to a fresh watermelon. This type of snow is common during the summer in alpine and coastal polar regions, such as the Sierra Nevada of California. Here, at altitudes of 10,000 to 12,000 feet (3,000–3,600 m), the temperature is cold throughout the year, and so the snow lingers from winter storms. When someone steps on the snow with algae, the footprints look red.