Luon Cave is situated on Bo Hon Island, 14 km south of Bai Chay Beach to the south. In front of the cave is Con Rua Islet, and the Sky Gate is on the right. Luon Cave is about 60 meters long and 4 meters wide. Height of the ceiling ranges from 2.5 – 4 meters up on tidal level. Therefore, it only can be accessed by small boat or kayak. 

Luon cave is a circular mountainous arc with a blue lake in the middle, and flows into the sea by a tunnel created by a spectacular and extremely mysterious cave. Through the beautiful entrance gate, tourists will meet a calm circular lake surrounded by luxuriant vegetation, craggy cliffs, shady ancient trees, and charming blooming orchids. It’s a brackish lake with calm and green sea water. Size of the lake is nearly 1 square kilometers. On the cliff are many fossilized freshwater snail shells proving that place used to be a deep freshwater valley. Especially, it’s highlighted with pristine setting of ferns, orchids and wild golden monkeys. And under the calm blue water surface is the vibrant life of the marine species such as shrimp, fish, crab, squid... 

The perfect combination of lime-stone mountains and jade-green sea makes Luon Cave a unique site to visit on Halong Bay. Furthermore, Luon Cave is a preferred place of tourists for kayaking.