Cat Ba National Park is a protected nature reserve that forms part of the Ha Long Bay – Cat Ba Archipelago World Natural Heritage site. Recognized by UNESCO as a World Biosphere Reserve, it boasts a remarkably diverse ecosystem featuring limestone rainforests, mangrove forests, coral reefs, and a system of magnificent caves. Activities to experience: - Conquering Ngu Lam Peak: The most popular trekking route takes you through the Kim Giao forest. From the summit (225m above sea level), you can enjoy a panoramic view of the undulating limestone forest. - Long-distance trek to Viet Hai Village: An 11–12km hike that tests your endurance, passing by Ao Ech (the island's largest freshwater mountain pond) en route to the remote, ancient village of Viet Hai. - Cave exploration: Nearby attractions include the 300m-long Trung Trang Cave—which cuts through the mountain and features stunning natural stalactites—and Quan Y Cave (Military Hospital Cave), a unique historical site that served as a wartime field hospital. - Wildlife observation: The park is the exclusive habitat of the Cat Ba Langur (golden-headed langur), one of the world's rarest primates and a species facing the threat of extinction. Entrance fees: Approximately 80,000 VND per adult and 40,000 VND per child. This ticket usually includes access to nearby caves.