Subterranea is a kingdom beneath the surface of the Earth. At one time it was the home of the Deviants. Subterranea consisted of a seemingly planet-wide network of caverns lying miles beneath Earth's surface. However, since Subterranea also extends to Monster Isle^[3] and Monster Isle has tunnels linking it to the center of the Earth,^[4] therefore, consequently Subterranea is also connected to the center of the Earth.

Twenty thousand years ago, the priests and intellectuals of the city of Netheria in the southern part of the Atlantean continent foresaw that Atlantis would be attacked by the Deviant Empire, which was based in Lemuria; therefore, the people of Netheria enclosed their city in a dome of an unknown plastic-like substance and both excavated and fortified their city's foundations. Consequently, when Atlantis sank, Netheria remained intact and its people survived, having discovered a means of recycling their air supply. Netheria sank down even more deeply over the years until it finally came to rest in a huge sub-sea cavern. The Netherians renamed their realm the Netherworld, and are now known as the Netherworlders.

The Fantastic Four discovered the Mole Man and a race known as the Moloids dwelling in these underground tunnels. The monsters of Monster Isle also called this place home.

Tyrannus also made Subterranea his home, which inevitably created friction between him and the Mole Man. In Subterranea, Tyrannus came upon a stockpile of abandoned Deviant technology, which he used to attack the surface world. On one such attack, he discovered the Fountain of Youth and on another, he became the lover of the Netherworld's queen, Kala.

The Lava Men are a race from Subterranea made of living lava. They first came into contact with the surface world when their king, Basallo, sent their supreme warrior, Molto, to investigate whether the surface world would become a threat to Subterranea. There, Molto was manipulated by Loki into attacking Thor, but after he came to his senses, he returned to Subterranea and informed his king that the people of the surface world were peaceful and, therefore, not a threat to them.^[5]

Alternate Realities[]

House of M[]

In the House of M reality, Harvey Elder was the king of Subterranea. He was building it into a paradise below the ground for his beloved Moloids, until the Fearsome Four came and destroyed them all.

Earth-828[]

In this reality, Subterranea is an underground civilization as its name suggests, inhabited by Moloids and Deviant Mutates, that was known to the surface dwellers only in stories and led by the so-called human the Mole Man.^[6]

Earth-1610[]

In this reality, Subterranea is located "1.4 miles below the surface world". It is a "cave system connected by millions of tunnels across the world." Arthur Molekevic located his original subterranean headquarters below the Baxter Building to keep an eye on its occupants, in particular his unrequited love, Sue Storm. Molekevic had discovered advanced technology from an ancient underground race that helped him develop this underground world.^[7] Molekevic also created his Ani-Men, who faithfully served him. Lava Men also exist in this underground system as well.^[8]