Two rivers, a mountain, and a really big tree

Though plenty of gates allow for travel between the Outer Planes, most planewalkers know a few other ways to get around. In particular, four major planar connections link several planes:

• the magical River Oceanus (running through a few of the Upper Planes),
• the River Styx (blood-red, dirty, and oily waters, running through all the Lower Planes in a twisted, aimless path),
• Mount Olympus (a mountain realm on the Plane of Arborea with a good number of planar pathways), and
• Yggdrasil, the World Ash (a gigantic plane-spanning tree, with its source in Ysgard, but with branches and roots spread throughout may planes, layers, and realms).

The Great Ring of the Outer Planes