Crater Lake: The Deepest Lake in the United States

Crater Lake is a caldera lake located in south-central Oregon, known as the deepest lake in the US and one of the clearest lakes in the country.

Crater Lake Stats

Lake NameCrater Lake
CountryUnited States
Surface area52.810
Maximum depth595.0
Average depth149.6
Lake typeCrater lake
Catchment area83.40
InflowsPrecipitation and snowmelt
OutflowsEvaporation and subsurface seepage
IslandsWizard Island, Phantom Ship
Shore length36.31
Residence time59453.7
Average discharge1.538
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Geography and Surroundings

The lake is the highlight of Crater Lake National Park, located at an elevation of 1883 meters, with a surface area of 53 km2. It partly fills up a caldera which has a depth of 655 meters and which was formed more than 7700 years ago after the collapse of Mount Mazama. Two large islands can be found on the lake: Wizard Island, which formed from a cinder cone, which erupted right after the crater started to fill up with water, and Phantom Ship Island, much smaller than the previous. The latter is famous for the colonies of swallows and several varieties of wildlowers and lichens which live on it.

The lake’s exact measurements are 8 km by 9.7 km across, with a caldera rim ranging in elevation from 2100 to 2400 meters. When considering maximum depth, the lake is regarded as the deepest in the country, second deepest in North America, and 9th deepest lake in the World. When taking into account average depths of some of the deepest lakes in the World, Crater Lake becomes the deepest of the Western Hemisphere’s lakes, and the third deepest in the world.

Limnologist Owen Hoffman built up a theory in which Crater Lake becomes the deepest in the World, if one only considers average depth into the equation, and only counts lakes whose basins are entirely above sea level.

One of the lake’s symbols is the “Old Man of the Lake”, which used to be a full-sized tree, but now is merely a stump. It’s been bobbing vertically in the lake for over a century, and since the water temperature is cold, it slowed the process of the wood’s decomposition.

The lake had no indigenous fish population, thus was stocked between 1888 and 1941 with a variety of fish, of which several species have already managed to form self-sustaining populations.

Geology and Formation

Mount Mazama, part of the Cascade Mountain Range, was built up for more than 400,000 years from dacite, andesite and rhyodacite. The caldera of the lake was formed after a massive volcanic eruption which occurred between 6000 and 8000 years ago, leading to the remission of Mount Mazama, when about 50 km3 of rhyodacite erupted. The lava eruptions occurring afterwards created the central platform of Wizard Island and other smaller volcanic features, such as a rhyodacite dome. Meanwhile, the caldera floor was covered in sediments and landslide debris fans and turbidite.

After the caldera cooled down, rainfall and snow contributed to the formation of Caldera Lake. Fumaroles and hot springs were highly active during this time. After the slopes of the lake’s caldera were a bit stabilized, the streams restored a radial drainage pattern on the mountain, which led to the appearance of the first forests on the previously barren landscape. Scientists estimate that it took about 750 years for the lake to fill to its present size. This mainly occurred when the region’s prevailing climate was less moist than currently.


The lake doesn’t have any tributaries, or outlets. Rain and snowfall compensate the evaporation and seepage rate of the lake’s waters at a rate at which all of the lake’s waters are totally replaced every 250 years. The lake has some of the clearest waters in the country, because of the absence of pollutants which would come into it through tributaries. The level of the lake fluctuates according to the weather conditions.

Clarity readings from a Secchi disk have consistently shown that the lake’s waters are very clean for any body of water. In 1997 scientists recorded clarity of 43.3 meters. The lake’s average pH levels range between 7 and 8. It has a relatively high level of dissolved salts, total alkalinity and conductivity.


The general climate of the area is subalpine, with an extremely rare Koppen classification of Dsc, due to high elevations and the strong influence of the North Pacific High during the summer. The area witnesses mild summers and dry winters, with cold and powerful influence on fthe Aleutian Low. This permits massive snowfalls in the region, with an average of 12.4 meters per year. The snow usually melts in mid-July.

During the winter of 1949-1950 the area witnessed an astonishing 22.48 meters of snow, while less complete snow cover records show a cover of 4.88 meters in the winter of 1981-1982. The heaviest daily snowfall occurred on the 28th of February 1971, measuring 94 cm. Average annual precipitation is 168 cm, whilst average annual snowfall is 13 meters.

History, Culture and Legends

The Klamath tribe has lived in the region for so long, its ancestors may have witnessed the collapse of Mount Mazama. They consider the area and the lake sacred. Local legend has it that Mount Mazama was destroyed during a battle between Skell, the sky god and Llao, the god of the underworld. The indigenous people used the lake in vision quests, which oftentimes involved dangerous tasks such as climbing the walls of the caldera. Those who succeeded were looked up to in the tribe, since they had more spiritual powers than others. The Klamath people still consider Crater Lake a highly spiritual site.

The first non-native to discover Crater Lake was John Wesley Hillman, an American. He came to the lake in June 1853 and referred to it as “Deep Blue Lake”. It was renamed at least three times, as Blue Lake, Lake Majesty, and later as Crater Lake.

Tourism and Recreation

The closest airport is located in Medford, 128 km away from Crater Lake. There are no public transportation routes currently serving Crater Lake area, but you can get to it by driving on mountain roads. Although the road sometimes might be bumpy, the sight of the lake will be totally worth it. The national park is always open, though some roads might be closed during the winter months.

Numerous lodging options can be found on site, such as Crater Lake Lodge, which has a total of 71 rooms and is open from May to October. Mazama Cabins have 40 units, open from May to early September. Mazama Campground boasts a total of 200 campsites, with extra facilities such as running water, flush toilets, picnic tables and fire rings. Lost Creek Campground is a more primitive campground, with a first come first serve basis.

The most beloved activities are cruising through the volcano area on daily boat tours and learning about the area’s natural and cultural history through guided walks. For the best views, don’t hesitate to hike up the closest peaks. You can also cycle around Rim Drive, which is usually open by July every year. Swimming is another popular activity. You mustn’t miss seeing the pinnacles, the needle-like formations called fumaroles, which formed under sheets of volcanic pumice before the collapse of Mount Mazama.

During the winter months some of the most popular activities are ranger-led snowshoe walking, cross-country skiing and snowmobiling.

Crater Lake Map