Situated on Bo Hòn Island, 14 km south of Bãi Cháy Beach is the Luon Grotto. In front of the grotto is Con Rùa ( Turtle) Islet, and the Sky Gate is on the right. Here the cliffs stretch vertically out of the pure blue and smooth water. At the water-level, an arched entrance leads to the grotto, just at the base of the island. The cave is 90 m long and 3.5 m wide. Passing through the pretty entrance, you come across a tranquil round lake, surrounded by luxuriant trees and high dangerous stone walls.