In Siberia, an ever deeper artificial hole was dug, the Kola Superdeep Borehole, which made it to a depth of 40,230 feet (12,262 m or 7.62 miles), or about a third of the way through the 22-mile-deep continental crust, over the course of two decades of drilling before the project was abandoned.
Of course, those are just the official records.
In reality, there is an entire world underground that we have literally barely scratched the surface of. A few brave souls have ventured further into the abyss and come back to report of a globe-spanning subterranean ecosystem, separated from our own by miles of sedimentary rock.
Gathering the various accounts available, I have created a very basic map of this realm, which is known as “Subterranea.” The underlying foundation of Subterranea is a ring of massive, basalt tubes, known as the “Symmesian Corridor,” extending for thousands of miles in a loop under the surface at an average depth of eight to ten miles (13-16 km) below sea level. Although this mostly places it within the Earth’s crust, it does extend into the mantle in a few places areas as it passes beneath the deep ocean. The Symmesian Corridor is at a minimum several miles across, and in some places are wide enough to accommodate a vast underground sea. Its walls are hardened with diamonds and unbreachable.
Weather and water currents rotate through it in a clockwise direction, circulating air and other vital resources throughout the vast underground realm. Whether the Symmesian Corridor is a naturally occurring formation or was engineered in some way is unknown. It is known that one section of the Corridor in the Indian Ocean was formed more recently than the rest, as the original segment in this region (approximate location noted with a dotted line) appears to have collapsed during the Great Cataclysm in the year 16,493 BCE.
Many smaller tunnel branches extend out from the Symmesian Corridor in all directions, including up and down, especially throughout the continental shelves. These are not shown on the map, as their location and exact nature is unknown. It is safe to say, however, that there are many hidden pockets of underground life that we know nothing about, which are connected more closely with Subterranea than with the surface world.
At certain points along the Symmesian Corridor, there are documented openings that extend all the way to the surface. We know this either because previous explorers have entered Subterranea at that point, or because unique fauna from Subterranea have made their way to the surface. These points are all identified on the map, and include:
- The Savage Land: a sheltered game preserve built by aliens in Antarctica. The Savage Land appears to be the source of the many dinosaurs and other prehistoric animals that now roam freely throughout Subterranea.
- Maple White Land: a secluded plateau in the Amazon Basin of South America. Explorer Maple White discovered dinosaurs and other prehistoric life forms here in 1901, and biologist George Challenger famously revisited the site two years later.
- The Valley of Gwangi: a valley surrounded by impassible canyon walls near Copper Canyon in the state of Chihuahua, Mexico. Local oral tradition tells of two Native Americans, Turok and Andar, who were trapped in the “Forbidden Valley” for over a quarter of a century, where they discovered all manner of strange beasts. More recently, around the turn of the century, a travelling rodeo was said to have captured a live allosaurus there, which they named “Gwangi.”
- K’n-yan and Yoth: two underground realms of legend beneath Oklahoma. K’n-yan connects to the surface and is a blue-lit realm inhabited by humanoid aliens. Yoth lies beneath it, within the Symmesian Corridor itself, and is a red-lit realm where Serpent People once dwelt and still may. Beneath that, it is rumored that there is an even deeper cavern, called N’kai, where the Great Old One known as Tsathoggua dwells.
- Mount Voormithadreth: a mountain in Greenland, honeycombed with tunnels. Once the epicenter of the ancient Hyperborean civilization, it is now buried under a glacier in Greenland.
- Mount Snæfellsjökull: a volcano in Iceland. In 1864, German professor Otto Lidenbrock traveled into Snæfellsjökull and through the northeastern portion of the Symmesian Corridor, emerging at Stromboli.
- Mount Stromboli: a volcano on an island off the coast of Italy, near Sicily, where Otto Lidenbrock and his party emerged in 1864 after traversing the Symmesian Corridor from Mount Snæfellsjökull in Iceland.
- The original location of Lemuria: the location of the microcontinent of Lemuria before the Great Cataclysm. It was originally home of a kingdom of Serpent People known as “The Dragon Kings,” and later by the human genetic offshoots known as Deviants before it was relocated during their earth-shattering battle with the Celestials in 16,493 BCE. There is no longer a surface entrance here, although it may be possible to find an undersea entrance to the Symmesian Corridor.
- Monster Island: a remote island in the middle of the Indian Ocean. Once part of the land of Lemuria, it was left behind as the rest of that microcontinent was violently dragged across the ocean floor during the Great Cataclysm in 16,493 BCE. The island has gone by many names over the years. Its official name is “Caprona,” after the Italian explorer Caproni, who was the first European to discover it in 1721. Polynesian islanders from Sumatra had already colonized the island, however, and in their language they called the place either “Skull Island,” due to the shape of a prominent outcropping of volcanic rock, or “Monster Island,” due to the island’s inhabitants, which includes dinosaurs, giant insects and all kinds of other strange creatures. The island’s most famous resident was King Kong, who was captured there in 1933. It was rediscovered in World War II, when both Axis and Allied forces saw it as a strategic location, but failed to capture what they then nicknamed “Dinosaur Island.” Most recently, the island was conquered by the subterranean Moloids.
On the map, I have also identified the location of several “sunken lands” of note. These include:
- Atlantis: a great submerged island in the Atlantic Ocean. Atlantis had once been known as Almaren, the home of the Valar (later known as the Vanir), before it was sunk by the evil Melkor (mentor of Sauron). The Valar later rose it back out of the sea and gave it to men to be the kingdom of Númenor, but they destroyed it again when men tried to set foot on their new home of Aman (the extradimensional world we now known as Asgard). Atlantis was eventually rebuilt into another great kingdom many generations later, but sank again in the Great Cataclysm when it would not heed the warning of Earth’s Sorcerer Supreme, Zhered-Na. Later, seven kingdoms would be founded within the submerged ruins of Atlantis by the aquatic humanoids known as Atlanteans (Homo mermanus). Far beneath the southern part of Atlantis lies the subterranean realm of “Netherworld.”
- Lemuria after the Great Cataclysm: the location of the sunken microcontinent of Lemuria (also known in this location as the Kerguelen Plateau) after it was relocated during the Great Cataclysm in 16,493 BCE. In their battle, the Celestials used a weapon that relocated the Deviants’ homeland thousands of miles across the ocean floor and sank it a mile underwater. It was abandoned by the Deviants, but was later repopulated by Atlanteans (Homo mermanus).
- Mu: a submerged island southeast of Japan and east of Taiwan. Mu was the site of one of the first human kingdoms, which was destroyed by dark magic and sank into the Pacific Ocean in 61,844 BCE. After the Great Cataclysm, the Deviants re-established their kingdom underground, eventually building their capital beneath the ruins of Mu.
- R’lyeh: the sunken stronghold of Cthulhu, one of the most powerful Great Old Ones. When Cthulhu and his kin were defeated by the Elder Gods (251.4 million years ago in the war that caused the Permian-Triassic Extinction Event), R’lyeh sank beneath the ocean floor with Cthulhu imprisoned within the city, “dead and dreaming.” R’lyeh is believed to be buried close to the “pole of inaccessibility,” the point in the Pacific Ocean furthest from any dry land on Earth.
- Thakorr: a submerged city in the southern Atlantic Ocean near Antarctica. When the Atlantean kingdom of Kamuu was sacked in the mid-19th century, its people moved south and founded a new city, which they named after their king, Thakorr. Eventually, that city too would be destroyed and most of the Atlanteans would return to Atlantis. But a few Atlanteans still dwell among the ruins of the city of Thakorr.
Finally, it is worth noting that there is a pocket dimension that seems to be tied to Earth’s core. This “Hollow Earth” dimension is often mistaken for being within the Earth itself, perhaps because many of the portals to it are buried far beneath the planet’s surface. (The only known portal to the Hollow Earth dimension from the surface of Earth is located near the North Pole.) However, it is an entirely separate universe, albeit apparently a finite one.
This dimension has many names, including “Pellucidar” and “Skartaris,” and is populated by creatures from Subterranea (including dinosaurs) as well as alien creatures native to that dimension. (Visitors from the Hollow Earth may be responsible for some UFO sightings in our world.) It appears much as a primitive version of Earth does, except that it is inverted: the ground is on the inside edge of the sphere, with gravity pulling outwards, while a stationary sun and moon hang motionless at the center of the sphere. Surrounding this “Hollow Earth” is at least 500 miles of solid rock, after which the dimensional boundary appears to end and one either doubles back toward the center again or appears in our dimension somewhere in Subterranea.
I hope this overview has given you a better view of this fascinating, if inaccessible, world we live above. Subterranea may be relatively nearby, but the technological challenges of reaching it make it even more difficult to reach than a manned mission to the stars. Still, as technology improves, I hope that someday we can establish steady contact with the world beneath our feet and the civilizations sharing this planet with us.