The largest rainforest in the world, the Amazon, exists between two rivers — but not in the way you might think. At ground level, the Amazon River and its tributaries weave their path. But above the canopy, bigger waterways are on the move. These flying rivers are almost invisible, but are essential to life on Earth. Iseult Gillespie explores how this crucial system keeps the rainforest alive. Lesson by Iseult Gillespie, directed by Upamanyu Bhattacharyya, Otter Studios.