The landscape of Umbria consists predominately of gentle hills and mountains. The major towns are Perugia and Terni. The rivers crossing the region are the Tiber, Nera and Velino. To the east of Terni is located an amazing waterfall "cascata delle Marmore". Also, in this area, is the greatest lake of the Apennines - Lake Trasimeno (128 sq.km.) but only 6m deep.