Most of the islands on Ha Long Bay are limestone and were formed over 500 million years ago, and are massed in the southeast and southwest. The schist islands scattered in the southeast have an average height of between 50-200m, and have a rich covering of flora.

Within the islands of the Bay there are hundreds of beautiful caves of different shapes and sizes, including many famous names such as Thien Cung, Dau Go, Sung Sot, Tam Cung and Bo Nau. Some of them are archaeological sites retaining tangible archaeological evidence, such as Dau Go, Bo Nau, Sung Sot, Soi Nhu, Tien Long, Me Cung, and Trinh Nu caves.

Population of Halong Bay

Halong Bay's inhabitants are distributed as follows:

+ In the World Heritage Area: is inhabited by the fishing communities, including the 4 communes of Cua Van, Cong Tau, Vong Vieng and Ba Hang with a total of over 1,600 people. This population belongs to Hung Thang Precinct of Halong City. They live on floating houses and boats and make their livelihood by fishing and aquaculture.

+ In the environs of the World Heritage Area: the residents of Halong City, Cam Pha Town, Van Don Island District and Cat Ba Island of Haiphong City.