Crater Lake National Park, Oregon

13. Crater Lake View

On a clear winter day, the smooth sapphire waters are an elegant contrast with the pristine snow. Come summer, the water is as blue as a pot of paint.

Crater Lake's intense color comes from its depth -- it's the deepest lake in the United States at 1,932 feet and the seventh-deepest lake in the world. It was formed approximately 7,700 years ago after 12,000-foot Mount Mazama erupted, an explosion 42 times greater than the 1980 eruption of southern Washington's Mount St. Helens. The caldera that formed after the volcanic eruption has since filled with approximately 4.6 trillion gallons of rainwater and snowmelt.