Halong Bay (descending dragon bay) is a UNESCO World Heritage Site, and a popular travel destination, in Quang Ninh Province, Vietnam. Administratively, the bay belongs to Halong City, Cam Pha town, and the part of Vân Đồn District. The bay features thousands of limestone karsts and isles in various sizes and shapes. Halong Bay is a center of a larger zone which includes Bai Tu Long bay to the northeast, and Cát Bà islands to the southwest. These larger zones share similar geological, geographical, geomorphological, climate, and cultural characters.
Halong 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 evergreenbiosystem, oceanic and sea shore biosystem. Halong Bay is home to 14 endemic floral species and 60 endemic faunal species.
Historical research surveys have shown the presence of prehistorical human beings in this area tens of thousands years ago. The successive ancient cultures are the Soi Nhu culture around 18,000–7000 BC, the Cai Beo culture 7000–5000 BC and the Halong culture 5,000–3,500 years ago. Halong Bay also marked important events in the history of Vietnam with many artifacts found in Bài Thơ Mount, Đau Go Cave, Bai Chay.
500 years ago, Nguyen Trai praised the beauty of Halong Bay in his verse Lộ nhập Vân Đồn, in which he called it “rock wonder in the sky”. In 1962, the Ministry of Culture, Sports and Tourism of North Vietnam listed Halong Bay in the National Relics and Landscapes publication. In 1994, the core zone of Halong Bay was listed by UNESCO as a World Heritage Site according to criterion vii, and listed for a second time according to criterion viii.