Tharsis Tholus lies on the eastern edge of the Tharsis quadrangle at 13.5°N, 91°W. It is about 800 km east-northeast of Ascraeus Mons, the northernmost of the large Tharsis Montes volcanoes. Lava from the Tharsis Montes and other sources within the interior of Tharsis completely surrounds Tharsis Tholus, forming a broad volcanic plain at the volcano's base.