Yuanli Township runs down to the sea; Sanyi Rural Township, its neighbor on the other side of the Huoyan Mountains, is ringed by hills. Facing them far away on the south bank of the river are Tachia Township and Houli Rural Township, both in Taichung County.
河床之北屬苗栗縣，隔著火炎山，靠海的苑裡鎮與山巒環繞的三義鄉比鄰，遙遙對戶著溪南岸屬台中縣的大甲鎮與后里鄉。