Ha Long Bay - Cat Ba Archipelago includes all stages of the marine submergence of tropical karst as well as three main types of caves - ancient marine frog-jaw caves, ancient karst caves and frog-jaw caves. On September 16, 2023, at the 45th Session of the World Natural Heritage Committee, the UNESCO recognised Ha Long Bay - Cat Ba Archipelago as the first Vietnamese inter-provincial site as a world natural heritage site. The recognition of Ha Long Bay - Cat Ba Archipelago as an international geological heritage by the International Union of Geological Sciences affirms the value of this heritage. The appearance of Ha Long Bay - Cat Ba Archipelago and its unique and famous geological and geomorphological values today are the result of a regional tectonic movement that lasted more than 500 million years./.