Mas O Menos: Class IV+ After passing under the Puente Futaleufu, the river enters into Mas O Menos. Mas O Menos is the largest rapid of the Lower Futaleufu and for good reason. A large landslide on river right has pushed an exuberant amount of boulders into the river, producing countless holes and enormous crashing waves. Mas O Menos changes from season to season as the winter water levels move boulders and eat away at the slide debris.