The Neath

"...where Hell is close, immortality is cheap, and the screaming has largely stopped… Welcome. Delicious friend."

The Neath is an immense, impossible cavern that stretches beneath the surface of Earth.

Deep, Dark, and Marvellous

"A cavern the size of Europe..."

The Neath - short for "beneath," and pronounced like so - is traditionally said to be roughly the size of Europe. The known and charted extent of it incorporates two continents, bordered by the vast Unterzee, which is dotted with islands. The cavern has walls and a roof, but because space is highly distorted in the Neath in all four cardinal directions, it is likely far larger than humanity can comprehend. Conventional distances and geography do not apply, and the Neath's position relative to the Surface is bizarre and often contradictory.

A map of the Unterzee. Not always reliable.

London and the Echo Bazaar are located on the western shore of the Unterzee, along the coastline of an unnamed continent. The Tomb-Colonies are north of the city, and the Iron Republic lies to the south. The Hinterlands and Hell are due west of London, further inland. To the southwest, the Dawn Machine has warped spacetime even further. The other primary landmass in the Neath is the Elder Continent, which comprises the southern edge of the Unterzee; its primary landmark, the Mountain of Light, shines from much further south. The northern edge of the Unterzee collapses toward a single point, the Avid Horizon, while the East is a seemingly infinite distortion of spacetime.

Throughout history, there have been many entrances or holes linking the Surface to the Neath; they were a more common sight in the past, and often became the subject of myth and legend. Several of these still remain:

• The Travertine Spiral is a massive, spiraling stone passage that joins the Neath with the Roof, and the Surface beyond.
• The Last Labyrinth connects to Shepton Mallet, a town in southwest England.
• A dumbwaiter links Balmoral to Edinburgh in Scotland.
• Lake Avernus served as the Roman mythical gateway to the underworld long before the construction of the Cumaean Canal, though the Canal later made passage far easier.

False-Seasons

"The Neath has no sunshine. None of the trappings of the seasons. Still it becomes hotter sometimes, more humid."

Because of the absence of the Sun, the Neath does not experience the conventional seasons seen on the Surface, and instead has its own peculiar cycle of "False-Seasons." False-Summer is the only one referred to by name; during this time, the Neath becomes hotter and more humid, as damp, warm fog blows in from the Unterzee. Certain phenomena also become more common, like wandering Parabolan mirages and outbreaks of spore-fever (ostensibly a fungal counterpart of hay fever). While it is not officially described as False-Winter, every December, "snow" begins to accumulate in London, and the city celebrates Christmas.

Certain seasonal patterns of bat colonies have been observed upon the Roof of the Neath, but these are not extensively described and may be a product of human artistic license.

Origins

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"The Creditor had not expected to be left behind. The Moon had not expected to be riven, or to be dependent on another for its light. The Sun had promised to make a star of them, and instead it made a pale, mocking mirror."

The Creditor

Long ago, the entity that was the Earth served a "fierce and brilliant" Judgement, presumably the Sun. It accepted its master's offer to ascend the Great Chain of Being and become a Judgement itself. In an event later called the Cataclysm of Silver, the Sun sent a Courier, a predecessor to the Bazaar, who struck the Earth with tremendous force. This Messenger, now known as the Shattered Herald, tore away a massive chunk of the planet, which rose into the sky and became the Moon. The remnants of the Earth which were left behind would become the Creditor, and the vast hollow resulting from the impact solidified into the Neath. The Sun repurposed the Neath as a hidden vault for its experiments (including its children by the Bazaar), placing the Creditor in charge of overseeing and protecting the Shames who were hidden from the Judgements' sight.

Guarding and regulating the Neath are a series of violations against the order of the Great Chain of Being, known as the Treacheries. There are said to be seven Treacheries, of which five are known: Clocks, Maps, Breath, Glass, and Hearts.

Historical and Cultural Inspirations

Across ancient civilizations, the idea of subterranean realms and underworld afterlives has appeared again and again. In Greek and Roman mythology, there was Hades, the shadowy land of the dead. Norse mythology spoke of Svartálfaheimr, the realm of dwarves hidden deep beneath the earth. In Hindu belief, Patala was an underground domain inhabited by serpents and demons, while Tibetan tradition told of Shambhala, a secret kingdom hidden beneath the Himalayas. The Neath draws from these mythological traditions, with notable similarities to Hades; much like the ancient warnings about the food of the dead, Surface travelers in the Neath are advised not to eat its food or linger too long if they hope to return to the Surface. It is a realm populated by all the strange, otherworldly, monstrous, and treacherous beings that one might expect from a mythical underworld.

However, the Neath is also influenced by theories from the days of the Scientific Revolution, notably Edmond Halley's Hollow Earth theory, which suggested that the Earth was made up of concentric hollow shells that each had their own atmosphere and possibly even their own forms of life. Halley had suggested this model to account for anomalous compass readings, but further experiments demonstrated the Earth's dense mass and disproved the hypothesis by the end of the 18th century. Modern geology and seismology have since confirmed that Earth possesses a solid inner core and a molten outer core, structures wholly incompatible with a hollow interior.

Despite being scientifically debunked, the Hollow Earth theory captured the imagination of writers and the public alike. It inspired a wealth of literature, famously including Jules Verne's Journey to the Center of the Earth, which was published in 1864 and popularized the idea of subterranean adventure. In the 1940s, Richard Sharpe Shaver published stories of ancient beings living in underground caves and secretly influencing human affairs; he claimed to draw from personal experience and encounters with the supernatural, and his ideas have inspired New Age imaginations — and conspiracy theories — ever since.

The persistence of these ideas suggests that there is something profoundly compelling about the mysteries that lie beneath our feet. Perhaps humanity is drawn, instinctively, to investigate anything hidden beyond its reach: anything deep, dark, and marvelous.