Lake and Peninsula Borough is a borough in the state of Alaska. As of the 2020 census, the population was 1,476, down from 1,631 in 2010. The borough seat of King Salmon is located in neighboring Bristol Bay Borough, although is not the seat of that borough. The most populous community in the borough is the census-designated place of Port Alsworth. With an average of , the Lake and Peninsula Borough is the least densely populated organized county-equivalent in the United States; only the unorganized Yukon–Koyukuk Census Area has a lower density.
Geography
left|thumb|View of [[Becharof Lake, in the Becharof National Wildlife Refuge]]
The borough has an area of , of which is land and (28.2%) is water. The borough contains Iliamna Lake, the largest lake in Alaska and third largest within United States borders, and occupies most of the Alaska Peninsula. Its land area is larger than that of San Bernardino County, California, the largest county in the contiguous Lower 48 states.
Adjacent boroughs and census areas
- Bethel Census Area, Alaska – north
- Kenai Peninsula Borough, Alaska – east
- Kodiak Island Borough, Alaska – southeast
- Aleutians East Borough, Alaska – west
- Bristol Bay Borough, Alaska – west
- Dillingham Census Area, Alaska – west
National protected areas
- Alagnak Wild River
- Alaska Maritime National Wildlife Refuge (part of the Alaska Peninsula unit)
- Sutwik Island
- Alaska Peninsula National Wildlife Refuge (part)
- Aniakchak National Monument and Preserve
- Becharof National Wildlife Refuge (part)
- Becharof Wilderness (part)
- Katmai National Park and Preserve (part)
- Katmai Wilderness (part)
- Lake Clark National Park and Preserve (part)
- Lake Clark Wilderness (part)