Long ago, lava from the nearby volcanoes choked this broad basin beneath the rim of the Cascade Range. Lava flows dammed streams, forming lakes. In other areas, streams flowed underground through the porous lava fields to well up as lake-sized springs. Still other lakes formed in the mouths of small, extinct craters.
Hwy 46, also called the Cascade Lakes Hwy, loops roughly 100 miles between high mountain peaks, linking together this series of lovely alpine lakes (though many of them aren't visible from the road). Cyclists pedal the road in summer, while skiers and snowmobilers take over during winter. There are several trailheads in the area – it's great backpacking territory.
Beyond Mt Bachelor, the road is closed from November to April or May, depending on weather.