The Arvenna River rises in the Vaudren uplands and flows south for roughly nine hundred kilometres before emptying into the Bay of Arvessa. Fed by mountain runoff, tributaries, and seasonal rainfall, its depth and flow vary considerably through the year. It is commercially navigable at least as far upstream as Arvenza, although summer water levels and local channel conditions can restrict heavier traffic. The river passes through many settled districts on its long course and has historically served as one of Valessar’s principal inland transport corridors, carrying bulk cargo, passengers, agricultural goods, and manufactured wares between the interior and the coast. Railway expansion has reduced its relative importance along some stretches, but the Arvenna remains essential for trade, irrigation, milling, fisheries, and local water supply.