Trong Cave

     Trong cave is a destination in route no.2 in Ha Long bay. It is opposite to Trinh Nu cave with the area of about 300m². This is one of cave archaeological relics of Soi Nhu culture, dating back from 18000 - 7000 years. At the northwestern and southeastern gates, traces of yellowish brown sediment layers and a layer of shells of Melania (a species of freshwater snails) and Cyclophorus (a species of mountain snails) can be seen. In addition, there are a small number of other freshwater mollusks as: cockleshells, pearl shells, etc.
       Entering the cave, besides watching stalactites and stalagmites, tourists can hear the sound of the wind blowing through rock slits and bouncing back the wall which creates drum-like sounds. So special and amazing!