Housed inside the bottom of a tall limestone cliff near Tongsai Bay, Viking Cave features a huge collection of bird nests used to make traditional Chinese Soup. Apart from this thriving industry, the Viking Cave also shelters ancient wall paintings of sailors and boats from the Scandinavian Drakkar Longship of the Vikings. The cave is closed to tourists and can only be seen from the boat.
Viking Cave is home to cave-dwelling birds, especially Black-Nest Swiftlets, which secrete strands of saliva harvested during breeding.