Toyako (Lake Toya) lies between Toyako-cho located in Abuta-gun and Sobetsu-cho located in Usu-gun.
The lake was created from the nearly circular Toya caldera and is the ninth largest lake in Japan in terms of surface area as for caldera lakes, it is the third largest one following Shikotsuko and Kussharoko.
Location of the center of the lake: 42o 36' N, 140o 51' E
Circumference: about 43km (east-west about 11km: north-south around 9km)
¥Area of the lake surface: 70.7km2
¥Deepest point: 179.7m
The lake absorbs the sun's heat during the warm season and radiates it out during the cold season. Wide, deep lakes are able to store large volumes of heat since they have a large volume of water. Therefore, these lakes never freeze and are referred to as ice-free lakes. Toyako is known as an ice-free lake that does not freeze even when it is extremely cold, similar to Shikotsuko.
Land and lake breeze (mirror surface)
On Toyako, the wind often blows from the lake to the land (lake breeze) during the day and from the land to the lake (land breeze) at night. This is because during the day, there is an updraft over the land, and the cool air flows towards the land. At night, there is an updraft over the lake because of the heat stored during the day, and air flows from the land to the lake. The wind changes direction twice a day ? morning and evening ? and when the wind stops, the beautiful surface of the lake appears like a mirror.
Nakajima is a lava dome island created around 50 thousand years ago from a volcanic explosion, and is part of a group of four islands ? O-shima, Kannon-jima, Benten-jima & Manju-jima. The islands have a rich nature that includes various type of conifer trees (including Yezo spruce Sakhalin fir), broad-leaf trees (including Acer mono, Japanese big-leaf magnolia) and wild birds (various birds belonging to the woodpecker family).