Located 30km east of Hai Phong city center, Cat Ba archipelago consists of 367 islands with rich and diverse natural ecosystems with outstanding biological values such as primeval forests, forests on limestone mountains. , Kim Giao forest, caves, mangroves, tidal flats, saltwater lakes, coral reefs and rare animals, recognized by UNESCO as a world biosphere reserve. Here, Cat Ba Island, also known as Pearl Island, is the largest of 1,969 islands in Lan Ha Bay.