Phú Yên Province
Several mountain passes function as geographic borders between the provinces of the region, with one or two provinces between two major passes. Major passes include the Hải Vân Pass on the northern border of the region (Da Nang), Binh De pass (đèo Bình Đê) between Quảng Ngãi Province and Bình Định Province, Cù Mông pass (đèo Cù Mông) between Bình Định Province and Phú Yên Province and Cả pass (đèo Cả) between Phú Yên Province and Khánh Hòa Province.