Crater Lake National Park

Mount Mazama collapsed into itself 7,700 years ago, and what filled the void became the deepest lake in the United States. Native Americans witnessed the eruption and kept it alive in legend. The lake has no inlet streams — every drop arrives as rain or snow, which is why the water holds that blue. Wizard Island, a cinder cone, rises from the middle of it. Established as a national park in 1902, it remains the only one in Oregon.