Ha Long Bay has an area of around 1,553 km2, including 1,960–2,000 islets, most of which are limestone. The core of the bay has an area of 334 km2 with a high density of 775 islets. The limestone in this bay has gone through 500 million years of formation in different conditions and environments. The evolution of the karst in this bay has taken 20 million years under the impact of the tropical wet climate. The geo-diversity of the environment in the area has created biodiversity, including a tropical evergreen biosystem, oceanic and sea shore biosystem. Ha Long Bay is home to 14 endemic floral species and 60 endemic faunal species.

500 years ago, Nguyen Trai praised the beauty of H? Long Bay in his verse L? nh?p Vân Ð?n, in which he called it "rock wonder in the sky". In 1962, the Ministry of Culture, Sports and Tourism of Vietnam listed H? Long Bay in the National Relics and Landscapes publication. In 1994, the core zone of H? Long Bay was listed by UNESCO as a World Heritage Site according to criterion vii, and listed for a second time according to criterion viii. Wiki