The Bwindi National Forest is a dense landscape of steep, green hills, narrow gorges and tumbling waterfalls. One of the most biologically diverse areas on Earth, the rainforest is so ancient it survived the last ice age! This unique space houses about half of the world's population of mountain gorillas, like these shown here, along with more than 120 other species of mammal. Bwindi is the only forest in Africa that is home to both gorillas and chimpanzees. (PAUL SOUDERS—GETTY IMAGES)