LakeAkan

This lake serves as a symbol of eastern Hokkaido and is also a tourist magnet. With a circumference of about 30 km, the lake reaches down 45 m at its deepest point, and covers an area exceeding 13 sq. km. Lake Akan is famous as the home of marimo, a Special Natural Monument, and its eastern shore features the beautiful silhouette of the towering Mt Oakan. Revel in the vista of the lake and mountains from the lakeside promenade.
Lake Akan Onsen includes many onsen (hot spring) hotels to the south of the lake, along with Ainu Kotan, the villages of the Ainu people indigenous to Hokkaido. The area features shops selling traditional handicrafts as well as a theater showing Ainu traditional dance, which is registered as a UNESCO Intangible Cultural Heritage.

Access Info
From Tancho Kushiro Airport, take the Airport Shuttle Bus for 1 hour and 15 minutes, and get off at Lake Akan Bus Center. The bus stops at each onsen hotel at Lake Akan along the way.

What are Marimo?
Marimo are balls of string-shaped algae gathered together by water currents at the bottom of the lake. These algae need sunlight to thrive, and will not grow unless they are in clean water that is clear enough for sunlight to pass through. The marimo in Lake Akan are designated as a Special Natural Monument because of their attractive spherical shapes. You can buy marimo in jars as souvenirs of Hokkaido, though these are actually made by collecting algae together artificially.

Cruising Lake Akan
While you're at the lake, why not embark on a cruise? A pleasure boat departs from a lakeside pier and tours the lake's scenic areas for about 1 hour and 25 minutes. The boat stops midway at Churui Island, where you can visit the Marimo Exhibition and Observation Center. The center presents exhibits related to marimo and gives you the chance to view natural marimo via a camera installed in the lake.
The cruises operate from 6:00am to 6:00pm between May and November (varies depending on the season; there are 8 to 11 cruises each day), and run every day during this period. Fees to board are 1,900 JPY for adults and 990 JPY for children.
Besides the pleasure boat, you can also rent a motorboat to cruise Lake Akan yourself. There's a total of 6 price options, offering fun cruises ranging from the Kojima course (500 JPY for 5 minutes per person) to the deluxe course (4,500 JPY for 45 minutes per person.)
* The motorboat prices above are the cost per person when two people ride. Visitors riding alone will be charged for two people.

Lake Akan Summer Lamp Festival
This event runs in July and August. You can write your hopes and wishes on a slip of paper inside a ball illuminated in green to resemble marimo, then cast it from the pleasure boat. These messages illuminate the surface of Lake Akan with a mesmerizing green glow on summer nights. The pleasure boat departs every evening at 7:50pm during the event and cruises for 55 minutes. It's 1,500 JPY for adults and 1,000 for elementary school children to join (includes the cost of the cruise).