Running northwest out of the highest reaches of the Tibellu hills, the Ossuelle is chilly, even around Midsummer. Its water is remarkably clear and sparkling, but almost too cold to drink.
The river is swift, and has many rapids and small waterfalls.
The Ossuelle is associated with death, probably due to its chill, but also because it runs past the Banelight Barrows. Moreover, sometimes one spots old skeletons clad in armour at the bottom of the river.
The river is unnavigable, save at its lowest' reaches, and unfordable all along, a good boundary between the old enemies Valsangé and Montcuivre.
Spanning the Ossuelle is a single stone bridge, known variously as The Old Bridge or the Ossuelle Bridge.