Ba Mun Island is a schist island belonging to the Minh Chau Commune, Van Ðon District. It stretches out parallel to Quan Lan Island, separated by the Ðoi Gate that runs in a north-east direction. It has the other name, Cao Lo Island. It is 15 km from the shore, 1,800 ha in area with more than 20 km long and narrow wide. It consists of a narrow stretch of earth and stone that runs east to west. The highest peak is Quít Mountain with a height of 397 m. The fauna and flora here are very plentiful. There are many rare species.
It is the only island in Halong Bay that is home to a primitive forest. There are countless species of plants and trees, some with giant trunks. This forest is also home to many rare animals such as chamois, deer and monkeys. It is said that many years ago tigers, panthers and elephants once resided on the island. In order to help preserve the forest, on 24 January 1997, the government recognised it as a national park.
Ba Mun Island is the only schist island with primeval forests in Halong Bay. On the island there are numerous rare types of timber. Some of them include Dinh timber, Lim timber, Sen Timber, Tau Timber. They are all trees standing there for many years, developing a huge circumference. Some grow so big that they require three to four people to hug around. Ba Mun Island is where many species of rare animals such as antelope, deer, monkeys, langurs and sea birds, migratory birds … are being protected. On 01/24/1997 Ba Mun forest has been recognized as Bai Tu Long national Forest.