Lake Akan

About Lake Akan

One of the lakes left when Old Lake Akan, a caldera lake formed by the Akan volcano 150,000 to 200,000 years ago, was shrunk and divided by the activity of Mt. Meakan and Mt. Oakan. It is the world's only place where large spherical marimo grow in colonies; marimo were designated a Special Natural Monument in 1952. Kokanee, native to this lake, and Sakhalin taimen, Japan's largest freshwater fish, also live here. It was designated a Ramsar Site in 2005.

Sources: Ministry of the Environment, Ramsar Site leaflet: Akan-ko, Ministry of the Environment, Akan-Mashu National Park: Highlights, Environment Agency of Japan, Lake Survey Report (1993) (sources in Japanese)

Lake data

Area

13.25 km²#11 in Hokkaido

Maximum depth

44.8 m#8 in Hokkaido

Average depth

17.8 m

Surface elevation

420 m

Transparency

5 m#13 in Hokkaidoas of the 1991 survey

Origin

Caldera lake

Lake type

Eutrophic

Fresh or brackish

Freshwater

Freezing

Freezes in winter

Unmodified lake

No

Natural park

Akan-Mashu National Park

Ramsar Convention

Ramsar Site

Lake number

0480number in the national lake survey

Sources: Geospatial Information Authority of Japan, Area Statistics of Prefectures and Municipalities 2026 (as of July 1), Geospatial Information Authority of Japan, Lake Survey (surveyed 1978), Environment Agency of Japan, 4th National Survey on the Natural Environment: Lake Survey Report (1993). Area and depth use newer figures from the Geospatial Information Authority of Japan where available. Origin, lake type, transparency, freezing and unmodified status are as of the 1991 survey.

Themes that include Lake Akan

• Caldera lakes
• Eutrophic lakes
• Freshwater lakes