Palus Epidemiarum /ˈpeɪləs ɛpɪdiːmiˈɛərəm/ (Latin palūs epidēmiārum Marsh of Epidemics) is a small lunar mare in the southwestern part of the Moon's near side. This feature forms a rough band of lava-flooded terrain that runs generally west–east, with a northward extension near the western end. It spans a shallow trough extending 300 by 120 km. The average thickness of the basalt is 200–250 m, with a maximum depth of 750 m. The feature lies to the southwest of Mare Nubium, and southeast of Mare Humorum.