州羽の海: the sea of Suwa (Lake Suwa), where Takeminakata yielded

おどろいたタケミナカタは、逃にげて、科野国しなののくにの州羽の海すわのうみまで行いき、そこで負まけを認みとめました。

Terrified, Takeminakata fled as far as the sea of Suwa in the land of Shinano, and there he admitted defeat.