The Songo river is one of the sources of Luzhma, it runs from Tunasozero lake.
Tumba is a source of Songo river. Its mouth is a shallow and narrow taiga river with numerous rafts. After passing Elejarvi lake the river becomes more full-flowing.
Tumba flows into Kerdano lake, which later goes into Unutozero. The western shore of the latter if formed with a high rocky ridge. A short (8 meters) but rough river Songo runs from Unutozero. The shores of the river are very picturesque.
