Crater Lake: The Deepest Lake in the US, Born From a Collapsed Volcano

America's National Parks, One at a Time · Nov 4, 2026 · 4m

Crater Lake formed about 7,700 years ago when Mount Mazama, an 11,000-foot Cascade volcano, erupted so violently it emptied its own magma chamber and collapsed into a nearly 4,000-foot-deep caldera. With no streams flowing in or out, the lake fills entirely from rain and snow and now measures 1,949 feet deep, the deepest in the United States. In this episode: the 1886 USGS survey that hauled a half-ton boat up the mountain to sound the lake with piano wire, Native American artifacts found buried under the eruption's ash, and William Steel's seventeen-year campaign that made Crater Lake…