Crater Lake is known to be the deepest lake in the United States and the seventh deepest in the world.
A maximum lake depth of 608 m (1,996 ft) was recorded by a group of USGS representatives in 1886 using piano wire and lead weight.
The maximum depth of 589 m (1,932 ft) was established in 1959 by the USGS using sonar measurement.
This depth is referenced at the surface elevation of 1,882 m (6,176 ft) .
But since its primary input source is dependent upon the climate, lake level is subject to abrupt changes.
Crater Lake partially fills the collapsed caldera of the ancient Mount Mazam Volcano.
The caldera is a bowl-shape depression of about 1,219 m (4,000 ft) deep.

The maximum depth of Crater Lake recorded at the time of the July 2000 multibeam survey was 594 m ( 1,949 ft) . The lake level had an elevation of 1,883 m (6,178 ft) above sea level at the time of the survey. The lake level of Crater Lake fluctuates according to the climate.