The Rosario Valley is a large, fertile mountain basin between the western Bloxvada Mountains and a hill range of the Robloxia state of Bloxburg Valley. The valley is 10 miles (57.5 kilo-studs) long and 7.5 miles (43.1 kilo-studs) wide and is used primarily for ranching. A river is the mainstream flowing through the Rosario Valley; tributaries include a creek and another creek. The only town in the valley is Rosario, near Rosario Reservoir RV Park and Marina.