Beautiful "Lake Toya" is the lake that becomes the center of Shikotsu-Toya National Park, and, following Lake Kussharo, Lake Shikotsu located in Hokkaido, it is the 3rd largest caldera lake in the country.
The lake that was born by a giant eruption approximately 110,000 years ago is approximately 43km in circumference (road circumference approximately 36km), water surface elevation 84m, lake area 70.7 km², average depth 117m, and is a non-freezing lake located in the northernmost part, but, in these days when the coldness is severe, ice formation can be seen in some parts.

The four islands (Ōshima・Bentenjima・Kannonjima・Manjūjima) located in the center of the lake are said to be solidified lava domes that uplifted by volcanic activity of the lakebed approximately 50,000 years ago, and are called Nakajima by their collective name. On the north side of Lake Toya, you can view the majestic peak Mount Yotei, and on the south side, Mount Usu, known for its volcano, and Shōwa Shinzan, and you can enjoy various sceneries throughout the four seasons.