Location: Located in a private gulf, on the northwest corner of Dau Be island, the southernmost island of Ha Long Bay, more than 25 km from the tourist port.
Characteristics: This is a circular lake surrounded by mountains. Across the foot of the mountain there are three caves filled with water, the lower cave has many stalactites hanging down. The caves are quite long and dark, the cliff near the cave has many beautiful flowers like orchid. At the end of the second cave there is an ancient starfruit tree that squirrels, monkeys, parrots usually come to eat. The third grotto has many bats, tourists can see the bottom of the cave where has many fishs. There are many boats waiting at the door to help visitors sightseeing, each carrying 6-7 people. It took 45 minutes to get in. Tourists must pay the boat at the price from 10-15 thousand VND / trip.