National park, southwestern Alaska, U.S., at the head of the Alaska Peninsula .
Occupying an area of 4,090,000 acres (1,655,000 hectares), it was proclaimed a national monument in 1918 after the eruption of Novarupta in 1912. The eruption converted the valley into a wasteland known as the Valley of Ten Thousand Smokes , and the volcanic crater later became a lake. The park abounds in wildlife, including large numbers of brown and grizzly bears.