Ha Long Bay - Cat Ba Archipelago is recognized as a World Geological Heritage site for its unique karst landscapes and diverse ecosystems The International Union of Geological Sciences (IUGS) has officially recognized Halong Bay - Cat Ba Archipelago as a World Geological Heritage site, a prestigious designation that acknowledges the area's remarkable geological and geomorphological significance. The announcement will be made during the 37th International Geological Congress, held in Busan, South Korea, from August 25 to 31, 2024.

Halong Bay and the Cat Ba Archipelago are renowned for their stunning landscapes, shaped by millions of years of geological evolution. The region showcases all stages of tropical karst marine submergence and features three distinct types of caves: old phreatic caves formed beneath ancient water tables, old karstic foot caves shaped by the lateral undercutting of cliffs, and marine notch caves, where sea levels erode rock formations, eventually forming wave-cut platforms. While Ha Long Bay illustrates the later stages of marine subduction, Cat Ba Archipelago adds unique geological value with its rare patterns of terrestrial and intertidal stages, some of which are globally unparalleled.

In terms of geological and geomorphological value, Halong Bay is an exceptional example of mature tropical karst, a process spanning over 20 million years. The formation of the bay was driven by a unique combination of factors, including thick limestone layers, a hot and humid climate, and slow tectonic uplift. As a result, Ha Long Bay showcases all the major forms of karst terrain, such as plains, valleys, funnels, peaks, and towers. Particularly noteworthy are the Fengcong and Fengling karst landscapes, which represent the final stages of tropical karst evolution.

The bay’s geological richness is also exemplified by its extensive cave system, formed between 2 million and 11,000 years ago. The interaction between sea flooding and erosion has made Ha Long Bay's karst formations unique, contributing to their global scientific significance. The area comprises 775 islands, primarily limestone, with 66 caves, 42 marshes, 81 lakes within the limestone formations, and 193 sandbanks. The discovery of a diverse fossil system further enhances its geological importance.


The neighboring Cat Ba Archipelago contributes to the region's diverse geological landscape. Its unique geological features, including diverse rock formations, minerals, fossils, and sedimentary structures, complement the karst field of Ha Long Bay. This western edge of the Halong karst field has been eroded by seawater, creating a distinctive form of karst that is one of the key elements making this region so geologically attractive.

Beyond its geological importance, Halong Bay - Cat Ba Archipelago is also celebrated for its ecological and biological diversity. The region boasts seven interrelated tropical and subtropical ecosystems, including primary tropical rainforests, caves, mangroves, coral reefs, and saltwater lakes. These ecosystems support a wide range of plant and animal communities, showcasing ecological processes that are still evolving.

The recognition of Halong Bay - Cat Ba Archipelago as a World Geological Heritage site is a testament to its unique combination of geological formations and rich biodiversity. This designation not only elevates its global standing but also reinforces the importance of preserving this natural treasure for future generations.