Spreading north and south along the eastern margin of the Indochina, from 8.5°N to 23°N in latitude, Vietnam covers approximately 329,500 km2, bordered on the north by China, on the west by Laos and Cambodia, and along its eastern coast by Tonkin Bay and the East Sea with the coastline about 3,000 km long. Its land area is long and narrow, with the widest distance being about 500 km between Mong Cai (Quang Ninh province) and north Dien Bien (Dien Bien province), and the narrowest distance, about 50 km between Ca Roong border gate (Lao and Vietnam border) and Dong Hoi (Quang Binh province).