The River Sphinx is the largest river in Osirion, flowing north from its twin sources, the Crook and the Asp River, to the Inner Sea. The majority of the nation's population lives along its banks, relying on the river for drinking water, transit, and silt from seasonal flooding for agriculture. Papyrus reeds and white lotus blossoms grow from its waters, and hetkoshu, a type of Osirian crocodile, lurk in its depths. Hippopotami are occasionally found, but they have been hunted to near-extinction. Hydras live in the river's delta, where they have long been a menace to local people.
The goddess Wadjet, the Green Empress, is the patron and embodiment of the River Sphinx and may live in the river's delta. Many temples to Wadjet may be found on the banks of the river.