Crater Lake National Park's Frequently Asked Questions
Crater Lake Institute - http://www.craterlakeinstitute.com/
Answer: Crater Lake is known to be the deepest lake in the United States and the seventh deepest in the world. The maximum lake depth of 589 m (1,932 ft) was established in 1959 by the USGS using sonar measurement. But since its primary input source is dependent upon the climate, lake level is subject to abrupt changes. 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 multi-beam 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.