Ha Long Bay is one of the most popular draws for visitors to Vietnam as well as a UNESCO World Heritage Site, renowned for its natural beauty. The bay is made up of thousands of limestone islands, many of them named for their distinct shapes, such as Voi (elephant) and Khi (monkey). These islands are home to diverse flora and fauna, including bantams, monkeys, antelopes, and lizards; the bay itself supports 200 species of fish and 450 species of mollusks. Four fishing villages also support around 1,600 people living on floating houses, while two of the larger islands, Tuan Chau and Cat Ba, house permanent residents as well as hotels and beaches.

Several of the islands in the bay are hollow, with enormous caves and grottoes. Hang Dau Go (“wooden stakes cave”) is the largest of these, named Grotte des Merveilles (“cave of wonders”) by 19th century French tourists. The huge cave is split into three chambers, accessible by 90 steps. Hang Dau Go earned its name in Vietnamese from the popular story of General Tran Hung Dao and his troops, who planted sharp wooden stakes in the riverbed to trap Kublai Khan and his Mongol forces at low tide. The legend of Ha Long Bay says that to protect ancient Vietnam from invaders, the gods sent a family of dragons who began to spit out jewels and jade. These jewels became islands that formed a great wall against the invading forces, sinking their ships as they hit the rocks that appeared by magic in the middle of the sea. After the battle was won, the dragons decided to remain on Earth – the mother dragon descended on the bay, and thereafter it was known as Ha Long (“descending dragon”).