The world's largest nature preserve has more than 15,000 trees, 530 species of reptiles, more than 100 varieties of birds, and 10 varieties of amphibians. The ecosystem, on the northern border of the Korean peninsula, is also home to the Suldrant area, one of the world's last active-reservoir coral reefs. Also known as "the lagoon" or "Seondal" after the era's land lord, Jangsong Yangtae, Seondal is one of the most biodiverse places in the world, an entire region of water surrounded by no man's land.