Thien Cung Cave sits on Dau Go Island in Halong Bay and is a natural cave attraction known for its stalactites and stalagmites. Three large chambers are filled with stalactites and stalagmites, lit throughout by colorful lighting. It is about 20 minutes from Tuan Chau Pier, and reaching the first chamber requires climbing 105 steps. The cave floor is slippery and the interior can be hot, so bring water and take care when moving.