Ha Long Bay is a known natural tourist resource officially listed by UNESCO as a protected item of the world heritage with over 3,000 rock islets exposed as a rare painting of nature.
Ha Long bay stretches from Yên Hưng district, past Hạ Long city, Cẩm Phả town to Vân Đồn district, bordered on the south and southeast by the Gulf of Tonkin, on the north by China and on the west and southwest by Cát Bà Island.
The bay consists of a dense cluster of 1,969 limestone monolithic islands, each topped with thick jungle vegetation, which rise spectacularly from the ocean. Several of the islands are hollow, with enormous caves. Hang Đầu Gỗ (Wooden stakes Cave) is the largest grotto in the Ha Long area. French tourists visited in the late 19th century and named the cave Grotte des Merveilles. Its three large chambers contain large numerous stalactites and stalagmites (as well as 19th-century French graffiti). There are two bigger islands, Tuần Châu and Cat Ba, that have permanent inhabitants. Both of them have tourist facilities, including hotels and beaches. There are many wonderful beaches on the smaller islands.
Some of the islands support floating villages of fishermen, who ply the shallow waters for 200 species of fish and 450 different kinds of mollusks. Many of the islands have acquired their names as a result of interpretation of their unusual shapes: such names include Voi Islet (elephant), Ga Choi Islet (fighting cock), and Mai Nha Islet (roof). 989 of the islands have been given names. Birds and animals including bantams, antelopes, monkeys, and lizards also live on some of the islands.
Almost these islands are individual towers in a classic fenglin landscape which height is from 50m to 100m and height/width ratios up to about 6.
Another specific feature of Halong Bay is the abundance of lakes inside the limestone islands, for example, Dau Be island has six enclosed lakes. All these island lakes occupy drowned dolines within fengcong karst.