It is situated on the south-west side the bay, 4 km from the wharf outside of Ha Long City. The way to Thiên Cung is a perilous one, covered on both sides by thick forest. After entering a narrow gate, the grotto’s 130-meter-long girth opens up. Getting in we are more astonished in front of the very animated and splendid beauty which is made from stalactite. On the east wall of the grotto, there is a grandiose and imposing picture with characters of tales.