Crater Lake

Lore & Background

Crater Lake was formed after Mount Mazama, part of the Cascade Range volcanic arc built up mostly of andesite, dacite, and rhyodacite over at least 400,000 years, collapsed in a massive volcanic eruption between 6,000 and 8,000 years ago. About 12 cubic miles (50 km³) of rhyodacite was erupted. The caldera was created around 7,700 (± 150) years ago. Since that time, all eruptions on Mazama have been confined to the caldera. Lava eruptions later created a central platform, Wizard Island, Merriam Cone, and other smaller volcanic features, including a rhyodacite dome atop the central platform. It is estimated that around 720 years was required to fill the lake to its present depth of 1,949 feet (594 m). Some hydrothermal activity remains along the lake floor, suggesting that at some time in the future, Mazama may erupt once again. The Klamath name for the lake is Giiwas. Klamath oral history tells of a battle between the sky god Skell and the god of the underworld Llao; Mount Mazama was destroyed in the battle, creating Crater Lake. The Klamath people used Crater Lake in vision quests, which often involved climbing the caldera walls and other dangerous tasks.

Reader's Guide

Crater Lake is significant as the deepest lake in the United States, the second-deepest in North America (after Great Slave Lake in Canada), and the eleventh-deepest lake in the world. When considering mean depth, Crater Lake becomes the deepest lake in the Western Hemisphere and the third-deepest in the world. Limnologist Owen Hoffman states that 'Crater Lake is the deepest, when compared on the basis of average depth among lakes whose basins are entirely above sea level.' The lake is 5 by 6 miles (8.0 by 9.7 km) across, with a caldera rim ranging in elevation from 7,000 to 8,000 feet (2,100 to 2,400 m) and an average lake depth of 1,148 feet (350 m). The lake features two small islands: Wizard Island, a cinder cone about 316 acres (128 hectares) in size near the western shore, and Phantom Ship, a natural rock pillar near the southern shore. Since 2002, one of Oregon's regular-issue license-plate designs has featured Crater Lake. The commemorative Oregon State Quarter, released in 2005, features an image of Crater Lake on its reverse. Recreational activities include hiking, biking, snowshoeing, fishing, and cross-country skiing. Fishing is promoted because the fish species (kokanee salmon and rainbow trout) are not indigenous to the lake.

Did You Know?

• No rivers flow into or out of Crater Lake; the total amount of water is replaced every 150 years by rain and snowfall.
• The lake's maximum depth of 1,949 feet (594 m) makes it the deepest lake in the United States.
• Crater Lake features two small islands: Wizard Island, a cinder cone about 316 acres (128 hectares), and Phantom Ship, a natural rock pillar.
• The 'Old Man of the Lake' is a full-sized tree that has been bobbing vertically in the lake for over a century, preserved by the low water temperature.
• In 1997, scientists recorded a record water clarity of 142 ft (43 m) using a Secchi disk.

Common Misconceptions (Editorial)

Some people assume that because Crater Lake is a volcanic crater, it is fed by rivers or underground springs. In fact, no rivers flow into or out of the lake; its water is entirely replenished by rain and snowfall, with the total volume replaced every 150 years. Another common misconception is that Crater Lake is the deepest lake in the world, when it is actually the deepest in the United States and ranks tenth globally for maximum depth.

Why It Matters (Editorial)

Crater Lake endures as a symbol of nature’s power to transform catastrophe into beauty—its deep blue clarity is a direct result of a volcanic collapse that reshaped the landscape thousands of years ago. The lake also carries lasting cultural significance, as the Klamath people’s oral traditions and vision quests connect this place to stories of gods and resilience, reminding us that landmarks can hold both scientific and spiritual meaning.