Old historical books often refer to Ha Long Bay by the names of An Bang, Luc Thuy or Van Don. It was in the late 19th century when the name Halong Bay appeared on a French Marine Map. Lagredin, a sub-lieutenant of the Avalanse, reported seeing a huge sea snake on Ha Long Bay. Many of the crew also witnessed this. Thus, emerged the European image of the Asian dragon.
Several of the islands are hollow with enormous caves. Hang Dau Go, better known as Hiding the Timber Cave, is the largest grotto in the Halong area. Its three large chambers contain large numerous stalactites and stalagmites.
Birds and animals including bantams, antelopes, monkeys and iguanas live on some of the islands.