Lakes · Hokkaido
Lake Akan
阿寒湖あかんこAkan-koThe lake of the marimo, between two volcanoes
Lake Akan (Akan-ko) is a caldera lake in the city of Kushiro, eastern Hokkaido, best known for its marimo – spherical green algae designated a Special Natural Monument. The hot-spring town on its shore has Hokkaido's largest Ainu community, Akanko Ainu Kotan.
Overview
Lake Akan lies in the Akan caldera in the western part of Akan-Mashu National Park, between the active volcano Meakan-dake to the south-west and the cone of Oakan-dake to the east. Four wooded islands rise from the lake, and the Akan River drains it south towards the Pacific at Kushiro.
The lake is famous for its marimo, velvety balls of green algae that grow in the lake's northern bays to diameters of up to around 30 centimetres – among the largest in the world. They are designated a Special Natural Monument and are the subject of an annual Ainu festival.
On the south shore, Akanko Onsen combines a hot-spring resort with Akanko Ainu Kotan, an Ainu village with craft shops, a theatre for traditional dance and performance, and a site for ceremonies.
Landscape and formation
The Akan caldera, some 24 by 13 kilometres, formed through a long series of large eruptions that ended more than 150,000 years ago. Later post-caldera volcanoes – Oakan-dake and the Meakan group – dammed the drainage and shaped today's lake, which was once larger and was divided when Oakan-dake grew. Neighbouring small lakes Penketo and Panketo were separated from Lake Akan the same way. Meakan-dake is monitored as an active volcano.
Highlights
Marimo of Churui Island
チュウルイ島Chūrui-tōIsland with an observation centre where marimo can be seen in tanks; boats call there on lake cruises.
Akanko Ainu Kotan
阿寒湖アイヌコタンAkanko Ainu KotanAinu village on the south shore with woodcarving shops and the Ikor theatre for traditional dance.
Bokke
ボッケbokkeBubbling mud pots on the shore reached by a nature trail from the onsen town; the name is Ainu for 'boiling place'.
Oakan-dake
雄阿寒岳Oakan-dake1,370 m volcano rising directly from the east shore.
Meakan-dake
雌阿寒岳Meakan-dakeActive volcano of 1,499 m south-west of the lake, climbed from Onneto or Meakan Onsen.
Ecology
Marimo occur in only a few lakes worldwide, and the large balls of Lake Akan are the best known. Their numbers declined in the 20th century through hydropower use of the outflow, logging and collection; since then they have been strictly protected. The surrounding forest is mixed conifer and broadleaf, home to sika deer and brown bears.
Flora
Marimo
マリモmarimoSpherical form of the green alga Aegagropila linnaei, rolled by waves on the sandy bed of the northern bays.
Sakhalin fir and Ezo spruce
Dominant conifers of the forests around the lake.
Fauna
Kokanee salmon
ヒメマスhimemasuLake Akan is one of only two native homes of kokanee in Japan; stock from here was introduced to many other lakes.
Ezo brown bear
Lives in the forests of the national park; trails carry bear warnings.
Culture
The Akan area has long been Ainu land, and the kotan at Akanko Onsen is today a centre of Ainu arts. The Marimo Festival, held each October since 1950, includes an Ainu ceremony returning marimo to the lake. Local conservationist Maeda Masana and his foundation preserved the forests around the lake from the early 20th century.
Marimo Festival
まりも祭りMarimo MatsuriAutumn festival with an Ainu ceremony to welcome and return the marimo.
Ainu Theater Ikor
アイヌシアター イコロAinu Shiatā IkoroTheatre in the kotan for traditional dance, inscribed as UNESCO Intangible Heritage, and modern stage works.
History
1897
Marimo are first recorded in Lake Akan by the botanist Kawakami Takiya.
1934
Akan National Park is designated as one of Japan's first national parks.
1950
The first Marimo Festival is held.
1952
The marimo of Lake Akan are designated a Special Natural Monument.
2005
Lake Akan is listed as a Ramsar wetland.
2017
The park is renamed Akan-Mashu National Park.
Through the seasons
Spring
The ice breaks up in April or May; snow remains on Meakan-dake.
Summer
Lake cruises to Churui Island, canoeing and hikes on the volcanoes.
Autumn
Autumn colour peaks in early to mid-October, the time of the Marimo Festival.
Winter
The lake freezes solid; ice fishing for smelt, snowmobiles and a winter festival take place on the ice.
Routes and trails
Lake cruise
Boats from the onsen town circle the lake and stop at Churui Island's marimo centre.
Bokke nature trail
Short forest walk from the town to the mud pots on the east shore.
Meakan-dake ascent
Half-day climb to the active crater, with views of the blue pond Onneto; access may be restricted when volcanic activity rises.
Practical notes
- Long-distance buses link Akanko Onsen with Kushiro and its airport in about two hours.
- Check the JMA alert level before climbing Meakan-dake.
- Winters are very cold; ice activities on the lake should follow local guidance.
Frequently asked questions
What are marimo?
Balls of green algae that form when waves roll the alga on the lake bed; at Lake Akan they reach around 30 cm across. They are protected as a Special Natural Monument.
Can you see marimo at Lake Akan?
Yes, at the observation centre on Churui Island, reached on the lake cruise, and in the eco-museum in the onsen town.
What is Akanko Ainu Kotan?
The largest Ainu community in Hokkaido, on the south shore of the lake, with craft shops, a theatre and ceremonies.
How do you get to Lake Akan?
By bus or car from Kushiro in about two hours; Kushiro Airport is the nearest airport.
Related
Sources
- 1.統計FAQ 日本の湖沼の面積 (opens in a new tab) — 総務省統計局
- 2.阿寒摩周国立公園 (opens in a new tab) — 環境省
- 3.Ramsar Sites Information Service (opens in a new tab) — Ramsar Convention Secretariat
- 4.釧路市 (opens in a new tab) — 釧路市