Crater Lake in the context of Wizard Island

Lake Tahoe (/ˈtɑːhoʊ/) is a freshwater lake in the Sierra Nevada of the Western United States, straddling the border between California and Nevada. Lying at 6,225 ft (1,897 m) above sea level, Lake Tahoe is the largest alpine lake in North America, and at 122,160,280 acre⋅ft (150.7 km) it trails only the five Great Lakes as the largest by volume in the United States. Its depth is 1,645 ft (501 m), making it the second deepest in the United States after Crater Lake in Oregon (1,949 ft or 594 m).

The lake was formed about two million years ago as part of the Lake Tahoe Basin, and its modern extent was shaped during the ice ages. It is known for the clarity of its water and the panorama of surrounding mountains on all sides. The area surrounding the lake is also referred to as Lake Tahoe, or simply Tahoe; its English name is derived from its Washo name, Dáʔaw. More than 75% of the lake's watershed is national forest land, covered by the Lake Tahoe Basin Management Unit of the United States Forest Service.

Mount Mazama (Klamath: Tum-sum-ne) is a complex volcano in the western U.S. state of Oregon, in a segment of the Cascade Volcanic Arc and Cascade Range. The volcano is in Klamath County, in the southern Cascades, 60 miles (97 km) north of the Oregon–California border. Its collapse, due to the eruption of magma emptying the underlying magma chamber, formed a caldera that holds Crater Lake (Giiwas in the Native American language Klamath). Mount Mazama originally had an elevation of approximately 12,000 feet (3,700 m), but following its climactic eruption this was reduced to 8,157 feet (2,486 m). Crater Lake is 1,943 feet (592 m) deep, the deepest freshwater body in the U.S. and the second deepest in North America after Great Slave Lake in Canada.

Mount Mazama formed as a group of overlapping volcanic edifices such as shield volcanoes and small composite cones, becoming active intermittently until its climactic eruption 7,700 years ago. This eruption, the largest known within the Cascade Volcanic Arc in a million years, destroyed Mazama's summit, reducing its approximate 12,000-foot (3,700 m) height by about 1 mile (1,600 m). Much of the edifice fell into the volcano's partially emptied neck and magma chamber, creating a caldera. The region's volcanic activity results from the subduction of the offshore oceanic plate, and is influenced by local extensional faulting. Mazama is dormant, but the U.S. Geological Survey says eruptions on a smaller scale are likely, which would pose a threat to its surroundings.

Crater Lake National Park is a national park of the United States located in southern Oregon. Established in 1902, Crater Lake is the fifth-oldest national park in the United States and the only national park in Oregon. The park encompasses the caldera of Crater Lake, a remnant of Mount Mazama, a destroyed volcano, and the surrounding hills and forests.

The lake is 1,949 feet (594 m) deep at its deepest point, which makes it the deepest lake in the United States, the second-deepest in North America and the tenth-deepest in the world. Crater Lake is often referred to as the seventh-deepest lake in the world, but this former listing excludes the approximately 3,000-foot (910 m) depth of subglacial Lake Vostok in Antarctica, which resides under nearly 13,000 feet (4,000 m) of ice, and the recent report of a 2,740-foot (840 m) maximum depth for Lake O'Higgins/San Martin, located on the border of Chile and Argentina. However, when comparing its average depth of 1,148 feet (350 m) to the average depth of other deep lakes, Crater Lake becomes the deepest in the Western Hemisphere and the third-deepest in the world. The impressive average depth of this volcanic lake is due to the nearly symmetrical 4,000-foot-deep (1,200 m) caldera formed 7,700 years ago (about 8 kya) during the violent climactic eruptions and subsequent collapse of Mount Mazama and the relatively moist climate that is typical of the crest of the Cascade Range.

Phantom Ship is a small island in Crater Lake in the U.S. state of Oregon. It is a natural rock formation pillar which derives its name from its resemblance to a ghost ship, especially in foggy and low-light conditions.