Mount Douglas is a
stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and per ...
located south of
Kamishak Bay, near the northeasternmost part of the
Alaska Peninsula
The Alaska Peninsula (also called Aleut Peninsula or Aleutian Peninsula, ale, Alasxix̂; Sugpiaq: ''Aluuwiq'', ''Al'uwiq'') is a peninsula extending about to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The ...
. It lies in the
Katmai National Park and Preserve
Katmai National Park and Preserve is an American national park and preserve in southwest Alaska, notable for the Valley of Ten Thousand Smokes and for its brown bears. The park and preserve encompass , which is between the sizes of Connecticut ...
in
Kenai Peninsula Borough
Kenai Peninsula Borough is a borough of the U.S. state of Alaska. As of the 2020 census, the population was 58,799, up from 55,400 in 2010.
The borough seat is Soldotna, the largest city is Kenai, and the most populated community is the ce ...
. The mountain was officially named in 1906 after nearby
Cape Douglas based on a 1904 report by USGS geologist G. C. Martin. The
Alaska Volcano Observatory
The Alaska Volcano Observatory (AVO) is a joint program of the United States Geological Survey, the Geophysical Institute of the University of Alaska Fairbanks, and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO ...
currently rates Douglas as
Level of Concern Color Code Not Assigned.
The volcano has a warm and highly acidic
crater lake
Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...
approximately 160 m (525 ft) wide. In 1982, the lake had a temperature of 21 °C and a
pH of 1, and temperatures of 114-118°C were measured in 1991. At the north flank of the volcano unglaciated and relatively uneroded lava flows are found. The last eruption is not known, but probably occurred during the