The world’s largest mangrove forest, Sundarban, spans the border between Bangladesh and India, but the countries don’t have a joint plan to manage the 3,700-square-mile area. The United Nations is hoping to change that. Two U.N. entities, the International Partnership Fund and the Educational, Scientific, and Cultural Organization, are providing funding to help Bangladesh and India develop a coordinated approach to saving the land. The Sundarban, which runs alongside the Bay of Bengal, is home to endangered Royal Bengal Tigers and the Sundari tree (which is found nowhere else in the world), among many other species. But the forest and its inhabitants are gravely threatened by illegal poaching, logging, increased salinity, and oil pollution — and that’s just for starters.