The Pisa is a river in north-eastern Poland with a length of 82 km and a basin area of 4,510 km2. It belongs to the Masurian Lake District of the Warmian-Masurian Voivodeship. The Pisa river flows from Lake Roś near the town of Pisz, and is a tributary of the Narew, connecting the Lakeland region with the Vistula.
