Hot sulfur spring, the water of which sinful women were permitted to use in "The Inferno"
A regio is a large area marked by reflectivity or color distinctions from adjacent areas, or a broad geographic region. On Io they are named after places associated with Io myth, places from Dante’s Inferno, or derived from a nearby named feature.
Image Source. Marker locations are approximate and may not always appear to align with image on map.