From the perspective of its surface, Azuyan appears to be a flat world. It lacks many of the telltale signs of a spherical planet that can be observed through simple methods.
The world is made up of many flat layers and seems to extend in all directions infinitely (as far as the ponies and peoples of the known seas can tell.) The Seafloor layer is deep, deep underwater and full of lava vents. Beneath it are supposedly lava filled caves, though none can venture into them. The Ocean layer above it is so deep that in most places light does not reach the seafloor. It does have topological structures like mountains and trenches, some of which near the surface enough to be visible.
On top of the ocean layer is the island layer. Islands in Azuyan are clusters of rock formed from lava spewing from the bottom of the sea. The hardened lava floats due to its unique structure. Some islands float under the sea and do not breach the surface, and in some unique magical cases they float in the air above the sea, but most float on the surface of the ocean itself. Most islands drift slightly in specific currents, and will be in slightly different locations at different times of the year. If certain island cluster together, they begin to maintain stable positions in the sea, so Clusters are the most common locations for civilizations to develop.
The Island layer is the top of the ocean layer and the botton of the Sky layer, which extends up into the sky as high as a pony can fly.
At the top of the Sky layer is a thin area where the Sun and the Moon orbit. The Sun rises in the east and sets in the west, though how it drops below the horizon when the horizon is theoretically infinite is anyone's guess. The moon is constantly in the sky, moving in a circular pattern around the near center of the known seas.
Above the sun and the moon lies the Aether. This clear gas is thick. It cannot be breathed and it cannot be flown through. Only light passes through. The only way to get through the Aether is to use the Gatelight. On the island layer it is on Reflection Isle and it connects to the space layer on the Zerax Isles.
Above the Aether layer is the Space layer. There is air here but it is very cold. It is full of rocky islands which float gently through the air, affected more by the gravity of stars than by the gravity from the lower layers. Stars are large luminous spheres full of a glowing liquid and covered with an impenetrable membrane. Rocky bodies that have collided with the surface of the star are prime locations for Spacefaring ponies to build their lives. There is another level of aether above the space layer.