River Styx

Known World and Tartarus. The souls of the dead of the Greco-Roman culture line up here to await their turn. Charon’s skiff is the only way to traverse the gateway. You can jump in and swim (although the water is icy cold and filled with all kind of supernatural germs), but without the skiff, there’s no way for you to pass over to Tartarus, no matter how far you swim. For all its foulness, Styx is in fact composed of holy water, thus forming an effective barrier for holding the underworld spirits back.