Cat Ba

Cat Ba National Park was established in 1986 in the city of Hai Phong, in northern Vietnam, and protects some 263 km² of the country's largest limestone island and of the islets that surround it in Lan Ha Bay. The archipelago comprises more than three hundred and sixty islands.

UNESCO recognised it as a biosphere reserve in 2004, covering 26,300 hectares, and on 16 September 2023, at the 45th session of the World Heritage Committee held in Riyadh, the archipelago was brought in through a significant boundary modification to the Ha Long Bay property, which was renamed Ha Long Bay - Cat Ba Archipelago. It was the first Vietnamese property to span two provinces. Ha Long Bay had been inscribed in 1994 for its aesthetic value and in 2000 for its geological value; the 2023 extension added the biodiversity criterion.

Together they constitute an outstanding example of mature submerged tropical karst, with limestone towers of vertical flanks rising straight out of the sea, arches, caves and coastal erosion features. The land portion of Cat Ba included in the property is around 13,000 hectares, surrounded by some 20,000 of coastal waters. The island is also home to the Cat Ba langur, endemic and one of the most threatened primates on the planet, with a population of barely a few dozen individuals.