Halong Bay is located on the Western side of the Gulf of Tonkin in Northeastern Vietnam. The bay is approximately 35 km (21 miles) Northeast of the port city of Hai Phong and approximately 170 km (105 miles) by road from the capital Hanoi. The town of Halong is situated on the coast to the North of the bay. The journey from Hanoi to Halong takes approximately 3.5 hours.
Halong Bay is formed by Cat Ba island to the South, Ngoc Hung and Van Canh islands to the East and the Vietnamese coastline to the North and West. The bay covers a total area of 1,553 square kilometers (600 square miles). Occupying the heart of the bay between Halong town and Cat Ba island, the central World Heritage area stretches for 434 square kilometers (167 square miles)