several paths of the Oceanus. The god Seker and his moveable realm Ro Stau spend most of their times adjacent to Isis's realm on the Oceanus. The Sumerian moon god Nanna-Sin travels the Oceanus in a great barque that is shaped like a crescent moon; in passing he provides a moon-like radiance to all on the banks of the river. Krigala is the first layer of the plane of the Happy Hunting Grounds, closest to the Astral, and through it the Oceanus flows in a relatively straight course (compared to its winding through Elysium) into Olympus. Ossa, the second layer of the plane of Olympus, is the outflow of the river Oceanus. There are often reports of huge, funnel-like maelstroms that lead directly back to Thalasia in an unending circle. River Styx The first edition Monster Manual II mentions that the River Styx "links the topmost layers of the Lower Planes, and its branches can be found anywhere from the Nine Hells to the Abyss". The river is a deep, swift, and unfordable torrent. Creatures coming into contact with the waters of the Styx instantly forget their entire past lives. The safest passage is by the skiff of Charon, boatman of the Lower Planes. Charon may be summoned only on the banks of the Styx, and he will appear with a large black skiff, and if requested he will ferry travelers to the topmost layer of any Lower Plane for a price. The charonadaemons are the servants of Charon, and pilot small skiffs along the Styx. Charonadaemons are normally found anywhere on the Styx and charge travelers a price to pilot their craft through the Astral and Ethereal planes as well as the Lower Planes. The first edition Manual of the Planes describes the River Styx as a means to travel from one Outer Plane to another, noting that "it flows through many portals in the lower planes and provides a regularly-used highway through these planes." The River Styx reappears in sourcebooks such as the Planescape Campaign Setting (1994), Planes of Chaos (1994), Planes of Law (1995), and the 3rd Edition Manual of the Planes (2001). Yggdrasil The first edition Manual of the Planes describes Yggdrasil as an astral landmark, noting that it is normally encountered by travelers from worlds that worship the Norse mythoi, but travelers from other Prime Material worlds can encounter the tree. It is a long-standing