Lake Saroma, connected to the Sea of Okhotsk, is the biggest brackish-water lake in Japan. Given its connection to the sea, the salinity of the water in the lake is almost the same as the sea. This lake belongs to Kitami City, Saroma Town, and Yubetsu Town. It’s the third biggest lake in Japan, after Lakes Biwa and Kasumigaura. In Ainu language, Saroma means a river with reeds, Saru Oma Petsu. Farming of scallops and oysters in the lake is ongoing and Hokkai Shimaebi prawns are caught. There are some remains such as shell mounds or houses which show us that ancient people lived here even before Christ. The annual 100km Lake Saroma ultramarathon is an annual highlight of the area.