|Aerial view; note Wizard Island against the western rim|
|Location||Klamath County, Oregon|
|Lake type||crater lake|
|Primary inflows||precipitation and snowmelt only|
|Primary outflows||evaporation and subsurface seepage only|
|Catchment area||23.3 sq mi (60 km2)|
|Basin countries||United States|
|Max. length||6 mi (9.7 km)|
|Max. width||5 mi (8.0 km)|
|Surface area||20.6 sq mi (53 km2)|
|Average depth||1,148 ft (350 m)|
|Max. depth||1,949 ft (594 m)|
|Water volume||4.49 cu mi (18.7 km3)|
|Residence time||157 years|
|Shore length1||21.8 mi (35.1 km)|
|Surface elevation||6,178 ft (1,883 m)|
|1 Shore length is not a well-defined measure.|
Crater Lake is a caldera lake located in the south-central region of the U.S. state of Oregon. It is the main feature of Crater Lake National Park and famous for its deep blue color and water clarity. The lake partly fills a nearly 2,148-foot (655 m) deep caldera that was formed around 7,700 (± 150) years ago by the collapse of the volcano Mount Mazama. Human interaction is traceable back to the indigenous Native Americans witnessing the eruption of Mount Mazama. There are no rivers flowing into or out of the lake; the evaporation is compensated for by rain and snowfall at a rate such that the total amount of water is replaced every 250 years. At 1,943 feet (592 meters), it is the deepest lake in the United States, and the seventh deepest in the world.
Crater Lake is known for the "Old Man of the Lake", a full-sized tree which is now a stump that has been bobbing vertically in the lake for more than a century. The low temperature of the water has slowed the decomposition of the wood, hence the longevity of the bobbing tree.
Two islands are in Crater Lake, with Wizard Island from a cinder cone that erupted after Crater Lake began to fill with water, and Phantom Ship Island with seven different trees living on it. There are also colonies of violet green swallows, and several varieties of wildflowers and lichens living there.
While having no indigenous fish population, the lake was stocked from 1888 to 1941 with a variety of fish. Several species have formed self-sustaining populations. Since 2002, one of the state's regular-issue license plate designs has featured Crater Lake. The commemorative Oregon State Quarter, which was released by the United States Mint in 2005, features an image of Crater Lake on its reverse.
In June 1853, the first European person John Wesley Hillman reported seeing what he named "Deep Blue Lake" in Oregon. The lake was renamed at least three times, as Blue Lake, Lake Majesty, and finally Crater Lake.
Dimensions and depth 
The lake is 5 by 6 miles (8 by 10 km) across with an average depth of 1,148 feet (350 m). Its maximum depth has been measured at 1,949 feet (594 m), which fluctuates slightly as the weather changes. On the basis of maximum depth, Crater Lake is the deepest lake in the United States, the second deepest in North America, after Great Slave Lake in Canada, and the tenth deepest lake in the world (Lake Baikal is the deepest). Crater Lake is often cited as the seventh deepest lake in the world, but this ranking excludes Lake Vostok, which is situated under nearly 13,000 feet (4,000 m) of Antarctic ice, and the recent soundings of San Martín Lake, which is located on the border of Chile and Argentina.
However, on the basis of comparing average depths among the world's deepest lakes, Crater Lake becomes the deepest lake in the Western Hemisphere and the third deepest in the world. Comparing average depths among the world's lakes whose basins are entirely above sea level, Crater Lake is the deepest.
The caldera rim of Crater Lake ranges in elevation from 7,000 to 8,000 feet (2,100 to 2,400 m).
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 that led to the subsidence of Mount Mazama around 5700 BC: about 50 cubic kilometers (12 cubic miles) 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 eventually 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 594 m. 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.
Crater Lake has a subalpine climate, with the extremely rare Köppen classification Dsc owing to its high altitude 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 523.5 inches (13.3 m) per year. 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 885.1 inches (22.5 m) of snow fell. The heaviest daily snowfall was 37.0 inches (0.9 m) on 28 February 1971.
|Climate data for Crater Lake|
|Record high °F (°C)||58
|Average high °F (°C)||33.7
|Daily mean °F (°C)||25.7
|Average low °F (°C)||17.8
|Record low °F (°C)||−21
|Precipitation inches (mm)||10.52
|Snowfall inches (cm)||104.9
|Avg. precipitation days (≥ 0.01 inch)||18||16||18||14||10||7||3||4||6||10||16||18||140|
|Avg. snowy days (≥ 0.1 inch)||15.0||15.3||15.9||11.4||6.4||2.1||0.3||0.2||0.9||4.8||13.4||15.1||100.8|
|Source #1: SHMI|
|Source #2: NCDC|
Water quality 
Due to several unique factors, most prominently that it has no inlets or tributaries, the waters of Crater Lake are some of the purest in terms of the absence of pollutants in North America.
Secchi disk clarity readings have consistently been in the high-20 meter to mid-30 meter (80–115 ft) range, which is very clear for any natural body of water. In 1997, scientists recorded a record clarity of 43.3 meters (142 ft).
Sacred significance 
The Klamath tribe of Native Americans, who may have witnessed the collapse of Mount Mazama and the formation of Crater Lake, have long regarded the lake as a sacred site. Their legends tell of a battle between the sky god Skell and Llao, the god of the underworld. 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. Those who were successful in such quests were often regarded as having more spiritual powers. The tribe still holds Crater Lake in high regard as a spiritual site.
See also 
- "Facts about Crater Lake". Oregon Explorer. Oregon State University. Retrieved 2009-02-05.
- "Crater Lake". Global Volcanism Program, Smithsonian Institution. http://www.volcano.si.edu/world/volcano.cfm?vnum=1202-16-. Retrieved 2008-12-18.
- Kartchnerand, W.E.; Doerr, J.E., Jr. (September 1938). "Wind Currents In Crater Lake As Revealed By The Old Man Of The Lake". Nature Notes from Crater Lake National Park XI (3). Archived from the original on 2008-06-11.
- "The Fish of Crater Lake". National Park Service. Archived from the original on 2010-02-21. Retrieved 2007-02-23.
- Goetze, Janet (August 26, 2002). "Crater Lake plates aglow with color". The Oregonian. p. B4.
- "The Oregon Quarter: The United States Mint". U.S. Department of the Treasury. Retrieved 2007-06-29.
- U.S. National Park Service. "Crater Lake National Park – Directions". Retrieved 2009-12-10.
- Tilden, Freeman (1968). The National Parks. New York: Alfred A. Knopf.
- Runkel, H.J. (1953). "Crater Lake Discovery Centennial". Nature Notes from Crater Lake National Park XIX. Archived from the original on 2008-12-04.
- Gibbons, Helen (September, 2000). "CMG Maps Bottom of Crater Lake, Oregon". U.S. Geological Survey. Retrieved 2010-05-16.
- Juillerat, Lee (November 29, 2007). "Into the Deep: Crater Lake's ranking as one of the world's deepest lakes varies by how list is determined". Klamath Falls Herald and News. Retrieved December 20, 2007.
- Bacon, Charles R; James V. Gardner, Larry A. Mayer, Mark W. Buktenica, Peter Dartnell, David W. Ramsey, Joel E. Robinson (2002). "Morphology, volcanism, and mass wasting in Crater Lake, Oregon". Geological Society of America Bulletin 114 (6): 675–692. doi:10.1130/0016-7606(2002)114<0675:MVAMWI>2.0.CO;2.
- Nathenson, Manuel; Charles R. Bacon, David W. Ramsey (2007). "Subaqueous geology and a filling model for Crater Lake, Oregon". Hydrobiologia 574: 13–27. doi:10.1007/s10750-006-0343-5.
- "Geologic History of Crater Lake". Oregon Explorer. Oregon State University. Retrieved 2009-02-05.
- "Crater Lake Nat'l Park H, Oregon Period of Record Climate Summary". Western Regional Climate Center. Retrieved 2012-04-17.
- "Station= CRATER LAKE NATL PARK HQ". National Climatic Data Center. Retrieved 2013-03-18.
- "Facts and Figures about Crater Lake". U.S. National Park Service. Retrieved 2012-01-03.
- "Park History". National Park Service. Retrieved 2012-01-03.
- "Crater Lake as Sacred Site". Sacred Destinations. Archived from the original on 2009-06-02. Retrieved 2007-06-16.
- Fire Mountains of the West: The Cascade and Mono Lake Volcanoes, Stephen L. Harris, (Mountain Press Publishing Company, Missoula; 1988) ISBN 0-87842-220-X
- Geology of National Parks: Fifth Edition, Ann G. Harris, Esther Tuttle, Sherwood D., Tuttle (Iowa, Kendall/Hunt Publishing; 1997) ISBN 0-7872-5353-7
- Eruptive history and geochronology of Mount Mazama and the Crater Lake region, Oregon, Charles R. Bacon and Marvin A. Lanphere, Geological Society of American Bulletin v. 118, p. 1331–1359 (2006) doi:10.1130/B25906.1
|Wikimedia Commons has media related to: Crater Lake|
- National Park Service: Crater Lake
- Crater Lake Data Clearinghouse of the United States Geological Survey
- Crater Lake Digital Research Collection. Oregon Institute of Technology. Retrieved 2009-11-12.