Catba is situated in Ha Long Bay, 50 km to the east of Hai Phong City, in Northern Vietnam. It is the largest of 366 islands in the Cat Ba Archipelago, and has a surface area of about 140 square km. The Cat Ba Archipelago shares the distinctive rugged appearance and scenic beauty of the Ha Long Bay Area that was declared a UNESCO World Natural Heritage Site, in 1994. The area is one of the best examples in the world of a Karst landscape invaded by the sea. Some 1500-2000 large and small islands and cliffs rise steeply from the shallow marine waters.