Crater Lake

Crater Lake is in Klamath County, around northwest of the county seat of Klamath Falls, and about northeast of the city of Medford. A Native American connection with this area has been traced back to before the eruption of Mount Mazama. Archaeologists have found sandals and other artifacts buried under layers of ash, dust, and pumice that antedate the eruption roughly 7,700 years ago. == Dimensions and depth ==

The lake is across, with a caldera rim ranging in elevation from and an average lake depth of . The lake's maximum depth has been measured at , which fluctuates slightly as the weather changes. Crater Lake is often cited as the seventh-deepest lake in the world, but this ranking excludes Lake Vostok in Antarctica, which is beneath about of ice, and the recent depth soundings of O'Higgins/San Martín Lake, which is along the border of Chile and Argentina. When considering the mean, or average depth of lakes, Crater Lake becomes the deepest lake in the Western Hemisphere and the third-deepest in the world. Crater Lake Institute Director and 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 average depths of Lakes Baikal and Tanganyika are deeper than Crater Lake; however, both have basins that extend below sea level." == Geology ==

Mount Mazama, part of the Cascade Range volcanic arc, was built up mostly of andesite, dacite, and rhyodacite over a period of at least 400,000 years. The caldera was created in a massive volcanic eruption between 6,000 and 8,000 years ago that led to the subsidence of Mount Mazama. About of rhyodacite was erupted in this event. 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 that was eventually created atop the central platform. Sediments and landslide debris also covered the caldera floor. Eventually, the caldera cooled, allowing rain and snow to accumulate and form a lake. Landslides from the caldera rim thereafter formed debris fans and turbidite sediments on the lake bed. Fumaroles and hot springs remained common and active during this period. Also after some time, the slopes of the lake's caldera rim more or less stabilized, streams restored a radial drainage pattern on the mountain, and dense forests began to revegetate the barren landscape. It is estimated that about 720 years was required to fill the lake to its present depth of . Much of this occurred during a period when the prevailing climate was less moist than at present. Some hydrothermal activity remains along the lake floor, suggesting that at some time in the future, Mazama may erupt once again. == Climate ==

Crater Lake features a subalpine climate, with the rare dry-summer type (Köppen classification Dsc) owing to its high elevation and – like all of Oregon – the strong summer influence of the North Pacific High. In the summer, the weather is mild and dry, but in the winter is cold and the powerful influence of the Aleutian Low allows for enormous snowfalls averaging per year and maximum snow cover averaging . This snow does not usually melt until mid-July, and allows for substantial glaciers on adjacent mountains. In the winter of 1949/1950 as much as of snow fell, while the less complete snow cover records show cover as high as occurred during another particularly unsettled winter in 1981/1982. The heaviest daily snowfall was , which occurred as recently as February 28, 1971; or more in one storm has occurred in both June and September. Hard frost is possible even into the summer, and the average window for freezing temperatures is August 20 through July 10, while for measurable (≥) snowfall, September 28 through June 11. ==Ecology==

Since the collapse of Mount Mazama due to a volcanic eruption formed Crater Lake, no fish inhabited the lake until William Gladstone Steel decided to stock it in 1888 to allow for fishing. Regular stocking continued until 1941, when it was evident that the fish could maintain a stable population without outside interference. Six species of fish were originally stocked, but only two species have survived: kokanee salmon and rainbow trout, with the former being the most plentiful. Crater Lake is also known for the "Old Man of the Lake", a full-sized tree which is now a log that has been bobbing vertically in the lake for over a century. The low temperature of the water has slowed the decomposition of the wood, hence its longevity. In 1987, scientists sent a submersible down to the depths of Crater Lake to obtain more information about the geology at the bottom of the lake, and inspect moss samples found in moss beds as deep as . Due to several unique factors, mainly that the lake has no inlets or tributaries, the waters of Crater Lake are some of the purest in the world because of the absence of pollutants. Clarity readings from a Secchi disk have consistently been measured as being , which is very clear for any natural body of water. In 1997, scientists recorded a record clarity of . However, in 2025, scientists recorded a clarity of , which means the lake's water getting cloudier and may be an indication of issues with the lake's physics, chemistry, and ecology. The lake has relatively high levels of dissolved salts, total alkalinity, and conductivity. The average pH has generally ranged between 7 and 8. == Sacred significance ==

The Klamath tribe of Native Americans, whose oral history describes their ancestors witnessing the collapse of Mount Mazama and the formation of Crater Lake, regard the lake as an "abode to the Great Spirit". Klamath oral history tells of a battle between the sky god Skell and the god of the underworld Llao (a prominent feature at Crater Lake is Llao Rock). Mount Mazama was destroyed in the battle, creating Crater Lake, called giiwas in the Klamath language. == Recreation ==

Located north of the city of Klamath Falls and northeast of Medford, Crater Lake can be reached from U.S. Route 97 on the east, on the southwest by Highway 62, and on the northwest by Highway 138. Crater Lake and the remnants of Mount Mazama can be seen from Rim Drive, a road that surrounds the caldera, which is the only part within the Crater Lake National Park where vehicles are permitted. Other activities include fishing and a 2-hour boat tour around the lake provided by a Park Ranger from Crater Lake National Park. As of 2026, the Cleetwood Cove Trail and Marina are closed for a three-year National Park Service rehabilitation project. Accordingly, lakeshore access, swimming, and public boat tours are suspended through the 2028 summer season. As the region lies within a national park area, collecting rocks within the vicinity is prohibited unless a permit is obtained. The park's facilities lie at Rim Village, at the southern edge of the caldera. No lodges, gas stations, or camping areas remain open from October through late May. Popular activities within Crater Lake National Park include biking, fishing, cross-country skiing, and snowshoeing. == See also ==