The Astral Sea

Geography

The Astral Sea is the largest division of the universe. It is composed of the "waters" that make up the universe and within these waters, all of creation can be found. It is organized into the Great Wheel Model however this map is more "metaphorical" and cannot be utilized as a literal map. However the most basic of facts are generally considered true. The Astral Sea has varying levels of reality which are based on location relative to the negative and positive planes. (Going forward this will be referred to as traveling "North" (towards the positive energy plane) or "South" (towards the negative energy plane).

The Northern edge of the Astral Sea is where positive energy is at its strongest this region is tumultuous and dangerous, when a ship or traveller arrives close enough they will firstly be healed of any wounds or diseases, then they will be strengthed each individual becoming much more powerful, and finally the healing will overcome the nature of life. Unnatural growth of life and flesh will sprout from any living being, bacteria spread to coat all material with a thin biofilm, plants grow to massive sizes with their leaves absorbing the positive energy, animals will become overwhelmed with tumorous growth as they become flesh mounds unable to die and growing for so long as they remain at the peak of the Positive Energy Plane. Finally, the edge of the Singularity is the peak of all energy, all beings gods, and mortals alike are endowed with endless, purposeless power as they join the endless light of the Universe.
The Westernmost edge of the Astral Sea is the focus of the lawfulness and negentropy of the universe. Many lawful gods make this area their home hosting many of the realms of the celestials. When approaching this edge travel becomes easier, the routes more systemic and routes clearer, travelling further will slowly degrade the free will of sentient creatures until they become one with the Astral dance performed at this point. Upon reaching the edge escape will slowly become impossible until the edge of the singularity is reached, finally, all material, life, and belief become one in a perfect, harmonious existence neither light nor dark simply "organized".
From the center of the Astral Sea one can find all of the material planes across the universe upon each material plane is layered a Feywild and a Shadowfell which exist North and South of the material planes respectively. This region of the Astral Sea is the only region that can be safely traveled. It houses an infinite number of crystal spheres each containing within them their own realms and planes. The center of the Astral Sea also houses on the edge of safe travel the elemental planes which surround the region as a series of islands preventing easy travel outside of the safety of the Astral Center.
The Easternmost edge of the Astral Sea is the home of entropy, the force of disarray and uselessness. Upon the very edge of this region, travel becomes more difficult, the Astral winds which propel Spell-jammers slow to the point of uselessness and further expedition requires some kind of internal propulsion. As one approaches the Singularity they will become confused and their guidance tools will provide inaccurate results. Further deeper the linear flow of time becomes dissolved and connection to time is lost, followed by the processes that support sentient thought, before finally, the very basics of physics and magic resulting in the total disassembling of all matter, cohesive "cause and effect" and understandable systemic reality.
The Southernmost edge of the Astral Sea is the Singularity of Negative Energy, negative energy being the opposite of life and energy. It is a black hole that pulls energy from the positive energy plane creating the flow of magic that travels through the world. When a traveler attempts to move through the Southernmost edge their health will rapidly deteriorate, this will present as fatigue and apathy at first, followed by more severe anemia and dystrophy. Magic also fails, any attempt at spellcasting inherently fails as there is no "magic" with which to utilize. Magic items that enter the negative energy plane are permanently depowered. At the point of no return, Spell-jammers become inoperative as they slowly drift deeper into the Negative Energy Plane. The final point of the Singularity reaches into the Negative Energy Plane and all life becomes impossible little to no protection is available to the living. The dense necrotic energy fills this point and prevents anything from entering, so whenever a particularly foolish traveler enters into the Singularity and an equivalent amount of Negative Energy is released from the plane the resulting creature is known as a nightwalker.
More information on Astral Cosmology can be found here Cosmology

History

When the Universe was first created it was simply a field of energies and auras spread flatly upon the infinite plane. This point is widely disputed and no clear answer is known, but it is believed that some force, god, or being intentionally reversed the entropy of the Astral Sea. This spread the Astral Sea into five points of near-infinite energy containing all matter, energy, and belief. These points are the five progenitor singularities of the Sea.
Firstly the Singularity of Positive Energy, this point was located at the Northmost point of the Astral Sea. 
Second the Singularity of the Organization, this point was located at the Westernmost point of the Astral Sea.
Thirdly the Singularity of Reality, this point was located at the perfect center of the Astral Sea.
Fourthly the Singularity of Entropy, this point was located at the Easternmost point of the Astral Sea.
Finally the Singularity of Negative Energy, this point was located at the Southernmost point of the Astral Sea.
It is believed that these points existed for the shortest of times before they were unable to contain their energies. Spreading instantly into each other colliding and blending with their opposite energies. This is the earliest point that any of the world Gods are verifiably existent (although almost all faiths claim their god was the progenitor forced to create the Singularities). The sole exception to the blending of energies was the Singularity of Reality which simply faded as it spread however it still has an obvious center, the Prime Material Plane. 
As this near-instant moment of blending ended the modern Astral Sea was created, within it the gods of the world gathered energy and matter to create their domains, and the elemental planes formed under the magical energy flowing from and too the positive and negative energy plane, the material planes under the effect of gravity collapsed into the crystal spheres they are now found in.

Type

Universe

Included Locations

• The Negative Energy Plane
• The Prime Material Plane