Deuteronilus Cavus is a roughly 120-kilometer-wide depression located in the Ismenius Lacus quadrangle of Mars, within the northern mid-latitudes of Arabia Terra. The name Deuteronilus is derived from Greek and means "second Nile," referencing the nearby Mamers Valles. Mamers Valles is a valley system that stretches over 1,000 kilometers, originating in the southern highlands and extending into the northern lowlands. The valley intersects Deuteronilus Cavus to the east. The Deuteronilus region is commonly referred to as fretted terrain — the transitional zone between the highlands and lowlands — characterized by knobs, mesas, branching channels, and depressions that often exhibit flow-like structures. Deuteronilus Cavus preserves a rich geological history, spanning from ancient Noachian terrain to Amazonian-aged surface deposits.