Sadogashima Island on the Sea of Japan, in the Chubu region of Niigata Prefecture, Japan.
Sado is the sixth largest island of Japan in area following the four main islands and Okinawa Island (excluding the Northern territories ocucpied by Russia Illegally).
The island consists of two parallel mountain ranges running roughly southwest–northeast, enclosing a central plain. The Osado range, in the North, is slightly higher, with peaks of Mount Kinpoku, the highest point of the island at 1,172 m, Mount Myoken, and Mount Donden. Kosado range in the South faces the Honshu coast. The highest point in Kosado is Ojiyama at 645 m. The plain in between is called Kuninaka and is the most populated area. The Kuninaka plain opens on its eastern side onto Ryotsu Bay, and on its western side onto Mano Bay, where the longest river, Kokufugawa, also read Konogawa) reaches the sea.
The island has a global symmetrical shape. Lake Kamo, on the eastern side of Kuninaka, is filled with salt water, and is a growing place for oysters.