Age of Heroes 5e
Olympus is the home of the Hellenic Gods and other members of that pantheon. The plane itself is spherical, just like a planet, but on a much grander scale. Relative distance doesn't seem to apply here, but it is known by some Gods that to traverse the circumference of the plane is no small task, even to them. There are three basic Realms on the plane of Olympus.
The first Realm, where the Hellenic Gods dwell is named after the plane itself. It is dominated by great mountains cut by sweeping passes and monstrous trees and other vegetation; arbors of grapes, untended orchards, and fields of wild wheat are just some examples. Many magical and fell beasts roam the wilds, challenging any who adventure within.
The second Realm is known as Aquallor (or Ossa). This great expanse of a sea is the outflow of the river Oceanus which began in the farthest Realm of Elysium, Thalasia. The waters of Aquallor are relatively shallow, as shallow as three feet over large areas, but up to a few hundred feet in other places. As such, the waters are warm and vast storms are common. Many water canyons can be found on this sea, great chasms into which the waters of Aquallor flow into from all sides like waterfalls, yet never fill up. Many of the more powerful creatures of the plane make their homes in these canyons. Aquallor is Poseidon's Realm.
Pellon, the third major Realm, is a dusty place of blowing white sand. Most of the Realm is temperate, but it can range from freezing cold to blistering heat. All things in this Realm are thickly covered with a dusty white sand. The Gods themselves have legends of ancient primordial beings who once dwelt here, but any evidence of such beings are now gone, presumably buried under the sands. What creatures and powers still live in this disintegrating Realm is unknown to even the most adventurous Gods.
The Hellenic Gods have located most of the open portals to other planes in Olympus and Aquallor. They appear as spinning crimson disks that do not reveal their egress for anything less than the most powerful divination spells. The Gods have surrounded the known portals with stone walls and iron gates, not so much to stop intruders as to slow the curious and prevent dangerous and stupid creatures from wandering in. The Gods do not mind extraplanar natives wandering about their plane, but they take a dim view on those with ill intent.
Most of the creatures and plants found on Olympus either fathered or were created from similar beings on the Prime. The creatures on Olympus, however, will be much larger and possibly intelligent.
One of the greatest features of Olympus is Mount Olympus, a continuous metaphysical conduit that reaches from Olympus, through the Prime, and into Hades. It is not known if the Ancients forged this mountain or if it has always been.
Most of the Gods live in palaces in various localities in Olympus according to their own needs and fancies. Zeus holds court on Mount Olympus and maintains a massive citadel of polished marble and gold at the highest pinnacle of the mountain. The Gods are served by spirits of those beings thought worthy of entry into Olympus.