The River Grismarie is also about 600 miles long and draws waters from the west facing side of the Grey Mountains. At its source, the river flows through the north edge of the Loren Forest and many Bretonnians regard the river as strangely enchanted. Its course takes it directly through a great lowland bowl, towards the Gisoreux gap, where the river is joined by the Ois and continues westward to the sea. Above the Ois, the Grismarie is navigable by large barges as far as Parravon, but sea-going vessels are restricted to the lower reaches and the wider, deeper Ois tributary. The river is crossable by ferry at Moussillon, but the only bridges on its entire length lie at Parravon and to the east of that city.