Some would say that the Abyss is a prison- they would be wrong. It is understandable to make such a mistake, as the realm is an infinite expanse of darkness where water doesn't drain into from the oceans connected to it, in fact, water in general seems to rise, moving to drain out of exit portals, creating puddles where Abyss entrances exist. With the only 'light' being born from portals into this realm, the abyss runs on some slightly different rules compared to the rest of reality. To enter the Abyss requires that one dives into the deepest points of the sea, into the darkest parts of a world where light of any kind has never touched it. It is only in these places that one can enter this realm, of course, for travelers with lanterns and sources of artificial light these portals shall shut sealed forever more as any light natural or artificial shall shut the gates into the Abyss. It is difficult to describe the transition into the Abyss, as the portals can only exist within complete darkness. As such, they have to be unseen by nature, the transition itself however, is near instant. One moment one is within the world, and the next they find themself on a Chain linking to the depths of the Abyss- escape at this point is somewhat easy, just turn around and climb out... just try not to fall.
Within the Abyss the inky blackness is so thick that it quite literally keeps non-living things afloat the deeper down you move, despite its intangible nature. Of course, this would be the point where the one traveling the Abyss would likely learn it's more hostile relationship with light. Should one use a torch, a spell, or some means to create light upon which to see, they will find themselves feeling as if they were burning while in the radius of the light as the darkness is scoured from their bodies. Furthermore, light itself is notably dimmer in the Abyss, barely able to exist above the most faint glow. Oddly enough, those within these depths can see perfectly, as if the darkness were the light of day. The Abyss is filled with chains made from a Smokey silver stone. Abyss-Stone is a deceptive and brittle substance that may appear as metal with it's luster and sheen, but is only as durable mere as stone. Every Chain in the Abyss is made from this stone, and each length of chain varies in size. Some can be as thin as a finger, others, can be monstrously large things that dwarf living beings and make mountains look like pebbles on the road. These chains Twist and turn through the Abyss, the largest ones creating their own gravitational pull in the process as that cloying darkness soaks everything within the realm. Were one to look closely at these chains, they would see that the links were perfect circles, each interlocked with one another with the implication of an unknown source keeping tension between the ends... but then the question becomes, what is anchoring these chains?
Should one rise to the highest points of the Abyss, and climb these chains- they would find that each Chain is linked to a portal into this realm, and should the chain be destroyed, the portal shall shut. Of course, that's only one of two linking points, and the question then becomes, what is it the chains attach to? Some of these chains will link into other portals to other worlds or openings within a single world, while others trail into the depths, hidden by that thick, cloying darkness. For the intrepid few who wish to explore this realm, be warned, the Abyss guards it's contents eagerly, devouring the living and wearing away at the things inside. Each and every one of those Chains will in time break, shattering and dropping into the darkness below as they slowly disintegrate into a fine silvery sand. However, the Abyss isn't a place of pure entropy either, as new chains can be forged from seemingly nothing- these links always appearing where new portals to this realm are created.
Dwelling within the Abyss is a dangerous thing, as it has a naturally hostile effect on things not born from it. Outsiders will find their bodies suffering from increasing levels of fatigue over time, their bodies and flesh being worn away, scrapes appearing over flesh as the mortal forms grow more and more fragile, the very darkness itself acting as a poison that slowly breaks down the Outsiders within its embrace. There are ways to ward off these effects of course, as the very material the Chains are made of works to deny this natural Entropy, taking the strain onto the material instead of the person... at least until the warding item disintegrates into a fine silvery white dust.
But what lies in the bottom of the Abyss? It's an endless desert of fine silver white sand, the dunes stretch and shift into the distance, mountains born from the fragments of fallen Chains of Abyss-Stone break the landscape, each lodged in the sand to slowly be buried as aeons pass. At the bottom most levels of the Abyss, things no longer decay, nor do they break apart under the effect of the darkness around them, instead they are Lost. One might assume gravity doesn't work, as lesser material items float into the air, threatening to rise far above to less Darkness dense areas of the Abyss. Living beings are only weighed down by their Souls, preventing them from floating away in turn. The Chains, or what parts of them make the trip, create the landscape and forge mountains and other such shapes. They create massive formations of not quite stone in an otherwise endless desert. Furthermore, this is the point where one would find that the Abyss's darkness can settle into a truly fluid state, and should one dig deep under the sands, they will find that the darkness itself has become solid.
To exist within the deepest depths of the Abyss is to be Lost to the world. People that once knew you will slowly forget you, as only the consequences of your actions and your creations will remain. Writings with your name will gradually grow more worn and increasingly likely to be damaged the longer you stay. To be Lost makes it difficult, if not impossible to escape, for one would need to climb from the bottom of the Abyss to the surface and return to the world of Creation, with all of gravity working to pull you back to the silver sands below. Those who escape the depths of the Abyss too late are doomed to find that without the Darkness of the Abyss, their bodies will slowly start to collapse into that silvery sand. There is a way to save oneself from this fate- and that is to be remembered. For as long as someone remembers the traveler in the Abyss, the victim in question shall not be taken and and claimed by the realm. As long as their written name is associated with them as a person, that link will prevent the Abyss from Claiming it's victim and allow them to escape. But be warry, for the Abyss wishes to keep all that it claims...