Environmental journalist Peter Thomson, founding producer and senior editor of National Public Radio's Living on Earth, combines introspection with objective reporting in this engaging account of his six-month pilgrimage to Siberia's Lake Baikal, the deepest, oldest and supposedly purest body of fresh water on earth. Thomson includes everything from thoughts about his failed marriage and his relationship with his brother and fellow traveler James to colorful impressions of the people he meets as he documents his quest, shattering the myth of the lake's reputed capacity to cleanse itself. Researchers tell him that the air and water are full of thousands of tons of pollutants and contaminants from Baikal's paper mill and nearby farms, industry and power plants. Tiny filter-feeding shrimp do cleanse the water, but in the process they move the contaminants into the food chain and concentrate them, so the fish eaten by the people living around Lake Baikal now pose a serious health threat. Nevertheless, many Russians continue to believe that the waters of the Sacred Sea are pristine. Thomson's book is a lucid and sobering reminder of the destructive effects human activity has on the planet.