Iliamna Lake is the largest lake in Alaska, with a surface area of about 1,012.5 square miles (2,622 km²), a length of 77 miles and a maximum depth of 988 feet. It lies at the north end of the Alaska Peninsula, drains through the Kvichak River into Bristol Bay and serves as the nursery for what the source calls the largest red salmon run in the world [1].
| Area | About 1,012.5 sq mi (2,622 km²) |
|---|---|
| Length | 77 miles |
| Maximum depth | 988 ft (301 m) |
| Outflow | Kvichak River to Bristol Bay |
| Ranking | Largest in Alaska; 7th in the US |
| Name origin | Dena’ina Nila Vena, “island’s lake” |
Size
Iliamna Lake is the largest lake in Alaska, the 7th largest in the United States and 24th in North America. It is up to 22 miles wide, averages 144 feet deep, holds about 27.7 cubic miles of water with a residence time of 7.8 years, and sits 46 feet above sea level [1].
Location and Drainage
The lake lies between Kvichak Bay and Cook Inlet, about 100 miles west of Seldovia. The Kvichak River is the primary outflow, carrying its waters to Bristol Bay [1].
Salmon
The lake is a nursery for the largest red (sockeye) salmon run in the world, and red salmon spend half their five-year life in fresh water, longer than any other salmon. Chinook salmon are also found there. The Kvichak is catch-and-release for trout and other native fish but not salmon [1]. See the entry on Southwest Alaska.
Wildlife and the Lake Monster
The lake has one of the few freshwater seal populations in the world. Local residents tell stories of an unknown aquatic creature, with speculation that it may be a white sturgeon or Pacific sleeper shark; the Anchorage Daily News once offered $100,000 for concrete proof [1].
Name and Villages
The name comes from the Inland Dena’ina name Nila Vena, roughly island’s lake. Six villages lie on its shores: Iliamna, Newhalen, Kokhanok, Pedro Bay, Pope-Vannoy Landing and Igiugig [1]. See the entry on the Dena’ina.
Portage Road
The 15.5-mile gravel Williamsport-Pile Bay Road links Pile Bay on the lake’s northeast side with Williamsport on Cook Inlet, letting small boats portage between Cook Inlet and Bristol Bay [1].
FAQs
How big is Iliamna Lake? About 1,012.5 square miles, the largest in Alaska.
How deep is it? Up to 988 feet.
Where does it drain? Through the Kvichak River to Bristol Bay.
What lives there? Sockeye and Chinook salmon and a rare freshwater seal population.
Is there a lake monster? Local stories exist, but no proof has been found.
Sources
More in Human Geography
Key facts
Quick checkWhich river carries Iliamna Lake’s water to Bristol Bay?Show answer
The Kvichak River
Sources
- Wikipedia. Iliamna Lake. 2026 (accessed 2026-11-12)
Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 12, 2026Researched and drafted with AI assistanceReport an issue