India, May 16 -- Even before he began travelling along the rivers of Ecuador, Canada and India for his new book, nature writer Robert Macfarlane spent hours beside the 10,000-year-old chalk springs of Nine Wells, near his home in Cambridge, England.

These streams drew life to the region, as rivers tend to do: at first, they fed the birch and hazel trees; then the deer and foxes; then people, kings and a city. "These streams are where a river is newborn," says Macfarlane, 48.

His new book, Is a River Alive? (May 2025; Penguin), focuses on what happens further downstream, in three massive river systems: the Rio Los Cedros (River of the Forest of the Cedars) in Ecuador, now under threat from gold mining; the choked, polluted and encroached...