The Sinoe River and its tributaries are the watery backbone of Sapo, draining most of the park's central forest and flowing south to meet the sea near Greenville. The rivers and their pools are where most wildlife activity converges — pygmy hippos wallow in quieter side channels, forest elephants drink at certain stretches, and the river edges hold dense bird populations.
Forest treks from Jalay's Town typically follow the river network for at least part of the route, fording smaller streams and following the more stable game trails along the banks. Outside of the dry season the rivers run high and crossings can be slow going; in the wettest months (August–September) treks deep into the park are sometimes impossible.