Omnispace first appeared to the world at large in the Chronicles of the Eternal Wanderer.
The sphere's primary.
Tymar is an inert fire world near the sun of Omnispace. It has no atmosphere and is uninhabited. At its core lie dormant elemental gates to the planes of fire and air.
Omni is the primary world of Omnispace. It is home to the Council of Nine, a group of Magi—nearly immortal, ultra-powerful mages—who rule the sphere from the Tower of Eternal Though.
The Tower is a one mile tall structure with a metallic exterior, and is located near the Port of Freedom, close to the center of the only major continent. The Port is the largest one on Omni. It gets wind from the Great Eastern Sea, though it is unclear how close the two are.
Omni's Eastern Realms are home to its oriental culture.
Many travellers consider Waterdeep of Toril the largest city in the known spheres. Many would contest this (Sigil of the Planes, Greyhawk of Oerth, New York of Terra), but in truth there is a city larger and more developed than Waterdeep. It is Glorin, the island city-state resting in the Great Western Sea of Paysage.
For millennia, none knew of Glorin because it was a fifty-mile wide island literally thousands of miles from nowhere. Rumors had it that, in the early years of the First Great Magical Age of Omni, sailors (travelling in archaic, seagoing vessels) tried to find an oceanic passage from one continent to another. (None knew back then that there was only one major continent on Omni.) These sailors, rumored to be ten score ships strong, set sail from Ancient Clifford looking for new land. Many hardships arose and met them on their journey; nearly half the crew was lost to various monsters and their kin. After months of travel, they happened upon the island.
Happy to finally find land, even though it was rather small, the settlers decided to build a settlement here. Unlike other worlds, where they harbor fears and trepidation about women on sailing ships, Omni considered women a good sign to have on a ship. The settlers named the island Glorin, an ancient word meaning "safe haven and home."
These settlers, all honorable warriors, mages and clerics of the old gods, decided to build a beautiful city. Although separated from the rest of the world, somehow they managed to develop a large fortification and city. When the rest of Omni was thrown into The Chaos Times, Glorin was spared. They remained a peaceful community, with a strong sense of commitment to one another.
When the Second Magical Age (and the coming of the Magi) came to Omni, the ruling council decided to set sail on their new and marvelous "Spelljammers" to map the world. Imagine their surprise when the found a city in the middle of the ocean! Contact was established, and friendly relations grew between the rulers of Glorin and the Magi Council. When Omni united a millennia past, Glorin gladly joined the world ruling body.
Glorin became a naval hub, as new ships (better at navigating the rough Paysage waters) began to sail the ocean and skies. Lord Monitor, when first assuming the head of the Council five centuries past, first travelled to Glorin for the Omniversal Peace Conference, the first step toward peace in Omnispace.
-from Omnispace, Chapter VII
Maclear is a waterworld two days out from Omni's orbit. The planet's inhabitants can breath water, and live mostly underwater. Their contact and trade with other worlds is done on floating cities held aloft by powerful magical devices.
There is also a reference to "Maclear Tea", which is probably made/ grown here. It may be made out of seaweed.
Maclear's inhabited moon. Population wiped out by a plague one year ago because help—via spelljamming ships—couldn't reach it in time.
Duranus is a small earth world. It is the primary food supplier for the sphere, and is home to the Omniversal Defense Force. It has a population in the billions.
This multi-layered air world is home to Omnispace's dragon population.
Karnak, the farthest planet from the sun, is a liveworld. Its inhabitants consider it to be sentient.
Sphereworld, a dyson sphere somewhere in Omnispace, is the "chessboard" or the gods. Whenever a new god wants entry into the sphere, he must have one of his heros pass various tests which the local gods set up.
The Tarangheti Sargasso lies outside of Karnak's orbit. Inside of it float many asteroids.
The Waterfall Nebula is located near the sphere wall. It looks like a multicolored wave "falling" from a cloud.
Omniversal Defense Force