Baie d'Halong, Bo Hon island

Situated in the centre of the UNESCO-declared World Heritage area, the Sung Sôt or Surprise Grotto is on Bo Hòn Island, and is one of the finest and widest grottoes of Ha Long Bay. Ascending to the grotto, the way is covered by trees and foliage, and consists of great paved stone blocks. Inside, it is partitioned into two chambers; the first one being similar to a wide theatre hall. Many stalactites hang from the high ceiling, with numerous possible forms and shapes. A narrow passage leads to the second rooms, where a flow of light meets visitors. The chamber is so immense it could contain thousands of people at one time.