The Abyss

"The allure of the abyss is inescapable. Even so, no one has managed to reach the end. A golden city that sleeps at the bottom of the abyss. Relics that surpass understanding. For 1900 years we have ventured into the darkness hoping to make greater and greater discoveries. The romance of a lost age and the arcane. Drawn to the great unknown, the abyss devours us."

The Abyss is a colossal pit discovered 1900 years ago around the islands of the southern ocean of Beolusk. The vertical hole has a diameter of around 1000 meters and it's at least 20,000 meters deep, with its exact depth being currently unknown. It possesses a unique ecosystem, wherein lie the remnants of an ancient, yet advanced civilization that made their home there in the distant past. Hiding countless treasures and relics of immense value inside, many explorers have challenged the mysterious Abyss. Some are treasure hunters looking for the Artifacts inside, and others are explorers determined to unveil the secrets it hides. In order to explore the Abyss, valiant cave raiders called Delvers were born, and the town of Orth was established at the edge of the abyss.

Even after so many years, the Abyss still contains many sections that have never been seen, as the hole carries many dangers. A hazardous habitat that defies common sense and otherworldly creatures that have adapted to its unique environment are some major obstacles that face explorers of the Abyss.

All over the Abyss there is a mysterious force field called the 'Lifeblood of the Abyss'. The force field acts as its main source of energy, carrying nutrients, producing light and sustaining life, in a similar fashion to the Sun. While it is present everywhere, it seems to be more prominent the closer one gets to the center. More savage and dangerous creatures are often found in areas where the force field is most prevalent and the branches of the vegetation always point towards the center of the hole, their main source of energy for undergoing photosynthesis. Delvers use this fact to guide themselves when they are lost. The force field itself is invisible to the naked eye, but it can be detected as a vague fog that limits vision for humans. The field is also constantly moving, following the consciousness of living beings. There are a few selected spots in the Abyss, usually far away from the center and in secluded areas, where the force field doesn't exist or is extremely weak.

The great pit also appears to have some form of time distortion, though it is unclear if this is a fact or merely a feeling. The White Whistle Ozen claims that the deeper one delves, the more your sense of time breaks, with the effect becoming extreme from the 5th Layer onwards. As an experiment she once descended for what she thought were a couple of weeks, but by the time she returned to the surface several months had passed. While there's little evidence to prove it, she considers it a possibility that time speeds up the more one descends.

The Curse of the Abyss
Though the Abyss is riddled with countless dangers and hazards, one of the greatest challenges facing delvers is, in fact, the ascent from it. This is due to a phenomenon called the Curse of the Abyss. The term refers to a series of symptoms that manifest upon ascending while inside the abyss, with its more scientific name being "Strains of Ascension". The effects of the curse manifest after ascending around 10 meters within the Abyss, and there's no way to avoid it through conventional means. The Curse affects all living things, however the creatures that inhabit the abyss have developed ways to sense its flow and avoid it.

The deeper one delves, the more severe the symptoms are, ranging from dizziness and nausea to intense pain throughout the body, loss of senses and even death. This makes the return trip from the Abyss extremely difficult, and it is not uncommon for delvers to perish on the way up. Particularly, the curse of the 6th Layer ("loss of humanity or death") makes the return journey physically impossible for humans.

The curse results from piercing the force field of the Abyss while ascending, although this fact is not generally known. Therefore, areas where the force field is weaker also result in the effects of the curse being less severe. In certain specific places, like Nanachi's Hideout and The Village of Ilblu, the force field isn't present at all, and so the Curse doesn't occur either.

Rare Phenomenon

 * Birthday Death Disease

The Blessing of the Abyss
An exceedingly rare and top secret phenomenon occasionally takes place within the Abyss under very specific circumstances. It was first discovered by the White Whistle Bondrewd when he was experimenting with the Curse of the 6th Layer. Much like with the Curse of the Abyss, the event occurs during the ascent, but two people are needed to witness the phenomenon. By having one carry all the burden of the curse onto himself (through the use of an artifact or another similar instrument) the other will be able to avoid the curse entirely. Through modifying several artifacts, Bondrewd utilized an elevator with two capsules that separate the curse and force it onto one of the two. Usually, if the one receiving the curse doesn't die midway through, this merely results in one of the two being spared the effects of the curse. However, during a certain experiment he discovered that a strong relationship of deep love between the two results in the event he called a "blessing" for the one that wasn't receiving the burden of the curse. While he couldn't explain the reason for this, it was factually proven.

The appearance of the blessed changes, growing fur all over the body and mutating some of their traits like the eyes or fingers. The blessing is not merely in looks however. The one gifted earns the ability to observe the force field of the Abyss, something that only the predators of the deep are able to see, and is an incredibly useful ability for delving in the pit. It also appears to increase their physical fortitude to some extent.

Abyss Faith
A religion that was formed around the Abyss itself, and it appears to be a very common belief among those that delve into the Abyss. Instead believing in a God, those that turn to this religion deify the Abyss itself. Because the bottom is unknown, it replaces their God and grants them hope for an after-life. It's based on the principle that if you lose your life within the Abyss, your soul will descend to the bottom and live as a form of spirit of the abyss. The unreachable depths of the pit makes people believe that it transcends life itself.

Layout
 Introduction 

Dante's Inferno reference: Riko and Reg are comparable to Dante and Virgil, the protagonists of Dante Alighieri's epic poem 'Dante's Inferno'. Dante got lost in the "dark wood", climbed a small mountain, was blocked by three beasts and rescued by the poet Virgil. The two of them then began their journey to the underworld, much like Riko and Reg do. Reg also bares similarities to the poet Virgil, who acted as a guide for the living Dante as they trespassed into Hell, and was sent by the Symbol of Divine Love, Beatrice. It was much within Virgil's power that Dante survived the initial submersion into Hell, allowing him passage by convincing the boatman Charon with words. Virgil was also sent by the prophetess Erichtho to retrieve a spirit from the deepest layer of Hell.

Each layer of the Abyss bares similarities to a to one of the Nine Circles of Hell described in the poem. The Curse of the Abyss is also comparable to the sins seen in each of the Nine Circles; the sins get increasingly more wicked as one delves deeper into the Inferno, with Satan himself lying at the very bottom.

1st Layer: Edge of the Abyss

 * Depth: 0~1350 meters.


 * Strains of Ascent: Light Dizziness and Nausea


 * Description: The first layer is the most shallow section of the abyss, right below the town of Orth. The environment is consistent and sunny, full of hollows in the grassy rockfaces and petrified trees. The wildlife consists of fantastical and mostly harmless animals.
 * Dante's Inferno reference: Dante's Inferno first circle is Limbo. Limbo is the intermediate state, where those who could not choose to rise to Heaven are imprisoned. Limbo is rather peaceful-appearing, with grassy fields and rivers, full of those who have committed no great sin. It was recorded that souls are not trapped in Limbo, and can leave it with certain interventions. This brings to mind the fact that if a Red Whistle delves deeper than the 1st Layer, no-one will come to save them.

2nd Layer: Forest of Temptation

 * Depth: 1351~2600 meters.


 * Strains of Ascent: Heavy nausea, headache and numbness of limbs.


 * Description: The Forest of Temptation is the first truly dangerous section of the abyss. The fauna and environment suddenly change, turning into a tropical rainforest with huge vegetation. The creatures that inhabit this layer are much more dangerous. Deeper in, there is an area known as the "Inverted Forest," where the trees grow upside-down and the wind blows hard. Here an Observation Camp was once built to serve as a resting point for delvers.
 * Dante's Inferno reference: The second circle is Lust (hence, The Forest of Temptation), this place is described as having terrible winds of a violent storm. It is recorded that the Second Circle is where the 'punishments of Hell proper begin'. This is reminiscent of the fact that the 2nd Layer of the Abyss is much more severe than the 1st. It is stated that the 2nd Layer isn't reached by much light due to the forcefield; the Second Circle of the Inferno was quoted to be 'a howling darkness of helpless discomfort'.

3rd Layer: Great Fault

 * Depth: 2601~7000 meters.


 * Strains of Ascent: Vertigo combined with visual and auditory hallucinations.


 * Description: The third layer consists of a 4 km vertical cliff, making it a highly challenging area to cross, save for the large cave network around the main shaft. Countless methods have been implemented by many in order to attempt a descent, to varying effects. Aerial predators are common, including Scarlet Maws.
 * Dante's Inferno reference: In the Third Circle, the beast Cerberus roams, to which he is described as 'the great worm'. This bears resemblance to the Scarlet Maws mentioned previously. Just like Riko and Reg, Virgil and Dante receive safe passage past the monsters, though that feat was mostly thanks to Virgil. The Third Circle is described as 'Gluttony', and that it symbolizes 'the cold, selfish and empty sensualities of the gluttons' lives'. This can be related to the 3rd Layer, which in turn is very empty and bleak when compared to others.

4th Layer: The Goblet of Giants

 * Depth: 7001~12000 meters.


 * Strains of Ascent: Intense Full-body pain, dizziness from pain and varying amounts of internal and external bleeding across the body.


 * Description: A strange, humid jungle of strong vines weaving to form giant concave discs that capture water from the air earn the 4th layer its name, the "Goblet of Giants." At 9000 meters marks the famous Garden of the Flowers of Resilience, an area filled with Eternal Fortunes, the trademark flower of the Abyss. A truly beautiful sight, though the danger from the beasts that dwell here is high.
 * Dante's Inferno reference: The Fourth Circle is 'Greed'. As Dante and Virgil enter this area, they are approached by the guard Pluto, who menaces them afterward. Pluto is comparable to the Tamaugachi, who attacks Riko and Reg. In the Poem, Virgil protects Dante from it. In the Fourth Circle, sinners who suffer from their greed are forced to push boulders, with which they joust, with just their chests. This brings to mind when Ozen and Lyza pushed the rock-like Curse-Repelling Vessel up from the 4th Layer. The Fourth Circle is also full of hoarders, which could imply Nanachi's habit of hoarding the belongings of dead Cave Raiders.

5th Layer: Sea of Corpses

 * Depth: 12001~13000 meters.


 * Strains of Ascent: Complete sensory deprivation, confusion and self-harming behavior.


 * Description: The thinnest layer of the Abyss vertically, being only 1000 meters deep, but the widest one horizontally, probably around 10 times wider than the town of Orth. It consists mostly of a large, monster-filled sea with some crystallized sections, held up by a thick layer of dense mud. This is the last layer of the abyss where it is possible to bear the curse and return alive and intact. An ancient ritual site, Idofront, which became a lab by Bondrewd and his crews acts as a gateway into the 6th layer, the point of no return.
 * Dante's Inferno reference: The Fifth Circle is 'wrath', and is portrayed as the 'stinking, swampy waters of the River Styx'. The river is held up by the bodies of the 'passively wrathful', much as the Sea of Corpses is held up by the bones of the dead. Within the Fifth Circle is the city of Dis, which is walled, and covered with high towers, the walls of which are guarded by fallen angels. The fallen angels refuse Dante and Virgil's entry, and is instead attacked. However, an 'angel' sent from Heaven allows them passage into the city. This 'angel' is comparable to Prushka, whose whistle form gave Riko and Reg entry into the 6th Layer.

6th Layer: The Capital of the Unreturned

 * Depth: 13001~15500 meters.


 * Strains of Ascent: Loss of humanity or death, or very rarely, the Blessing.


 * Description: A White Whistle's last dive. A human who tries to ascend from the 6th layer either succumbs to death, or is deformed beyond recognition, hence the name, "The Capital of the Unreturned." In Orth, there is a rumor about a Golden City at the bottom of the abyss, which originated from the 6th layer, where the ruins of a majestic city sleep undisturbed. It is not uncommon to come across creatures of an Irrational danger level here. In a secluded area of the 6th Layer, an entire Village inhabited by Narehate called Ilblu was formed.
 * Dante's Inferno Reference: The Sixth Circle is 'heresy'. In this Sixth Circle, heretics burn in flaming tombs of which they can never escape from. The fact that 'heresy' is the Sixth Circle's sin can relate to the village of Ilblu and the narehate who live within it. The word 'heresy' comes from the old Greek word  'haireomai' meaning 'to choose' or 'choice'. Seeing that the Ilblu Narehate take on the form of their desire, but can never leave the village, was very much their 'choice'.

7th Layer: The Final Maelstrom

 * Depth: 15501~????? meters.


 * Strains of Ascent: Certain death.


 * Description: The final known layer of the Abyss. Not much is known about it but there are many rumors about it. Some white whistles have claimed that from above it can be seen something shaped as a ring. It was here that Lyza wrote she first spotted what is apparently Reg.
 * Dante's Inferno reference: The Seventh Circle of the Inferno is 'wrath'. Wrath is divided into three 'rings', much like the ring in the description in Ozen's explanation of the 7th Layer.

The Deepest Point

 * Depth: +20000 meters.


 * Strains of Ascent: ???


 * Description: No-one has reached the deepest point but it is theorized that it's beyond 20000 meters deep.
 * Dante's Inferno reference: If the author is using Dante's Inferno as reference of the story, then the abyss is possibly to have 9 layers (including Limbo and the Sixth Circle of Heresy).

Trivia

 * The Abyss is sometimes referred as the netherworld.
 * The Abyss's layers are comparable with Dante Alighieri's 14th century poem (Dante's Inferno).
 * The map of the Abyss was the first concept of the series drawn by Akihito Tsukushi, and he was inspired by role-playing games like Wizardry that he used to play as a kid.
 * All throughout the Abyss, Delvers report findings of human remnants from civilizations past. All of the skeletons have their hands clasped in prayer. Little is known about their origin.