In a world where almost everywhere has been explored, it is exciting to read about the world's deepest ravine, almost inaccessible, full of vigin forest, strange plants, and animals, and still not fully explored either by Chinese or Westerners. Frank Kingdon Ward explored it in the 1920s, in what was then Tibet, leaving a stretch of several miles unknown to all but the local tribes. His original book is reproduced as the core of the present one (with some editing of his words to remove comments that would today be viewed as unacceptably racist). There are also accounts of earlier explorations of the region, including the wild borderlands of India to the south, choked by subtropical forests and then populated with violent tribes (this border region is still disputed by China and India). Kingdon Ward was a botanist, focusing on the plant life of the gorge, whereas the new book gives accounts by modern explorers and covers additional aspects, such as Tibetan religion. There are some fascinating photographs: black and white ones by Kingdon Ward and modern color ones. Two I particularly like are the same view of mountains and old-growth forest taken from a cave where Kingdon Ward camped in the 1920s. One is Kingdon Ward's photograph, and the other is taken some 75 years later, with individual trees grown larger, a large glacier melted away, and the treeline higher up the mountains. Recent, separate expeditions by Western and Chinese teams in the 1990s have shrunk the unexplored stretch of the gorge to about three miles. The discoveries of the Westerners are described and illustrated in the book, including a "new" waterfall. Unfortunately, though, politics make an unwelcome intrusion at the end of the story.