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- For the song, see The Hollow Earth.
Unto the breach.
— David Lind before attempting to enter the Hollow Earth (Godzilla vs. Kong: The Official Movie Novelization)
The Hollow Earth is an underground location in the MonsterVerse. First theorized to exist in Kong: Skull Island, it subsequently appeared in both Godzilla: King of the Monsters and Godzilla vs. Kong. It is made up of cave-like tunnels and passages that lead to a large, inner world. It is held by Monarch to be the evolutionary source of the Titans. Known entrances to the Hollow Earth include Skull Island, the Mariana Trench, and Antarctica.
William Randa recruited Houston Brooks into Monarch after reading a paper he wrote in support of the maligned Hollow Earth hypothesis: the existence of "massive underground spaces isolated from the surface world." Randa theorized that one such space existed beneath Skull Island, and that this lost world was the home of countless monsters. During Monarch's expedition to the island, seismic charges dropped by the Sky Devils helicopter squadron on Skull Island showed that the bedrock was nearly hollow. After Kong attacked the helicopters, they learned from Hank Marlow that the charges had disturbed the massive, subterranean Skullcrawlers. Nonetheless, Brooks's theory remained unverified, and gradually fell out of favor at Monarch.
As Monarch raced to Antarctica to stop Alan Jonah from awakening King Ghidorah, Godzilla fell off their sensors. Dr. Rick Stanton theorized that he was using underwater tunnels in the Hollow Earth to swiftly travel. After the U.S. military used the Oxygen Destroyer to end a battle between Godzilla and Ghidorah near Isla de Mara, Godzilla retreated to an ancient underwater temple in the Hollow Earth to recover. Monarch tracked him there via submarine with the help of Mothra, and Dr. Ishiro Serizawa sacrificed himself to detonate a nuclear weapon, revitalizing the Titan. After Godzilla killed Ghidorah, Monarch made plans to explore the Hollow Earth, hoping to discover the origin of the Titans.
Prior to 2024, Monarch attempted an expedition into the Hollow Earth led by Corporal David Lind. However, the sudden gravitational inversion experienced upon entering the Hollow Earth proved fatal and killed David along with the rest of the expedition. David's brother, Monarch geologist Nathan Lind, published a book about the Hollow Earth to poor reviews and sales. Lind eventually left Monarch for Denham University of Theoretical Science, where he was approached by Apex Cybernetics CEO Walter Simmons and Chief Technology Officer Ren Serizawa. They reported that recent scans of the planet showed a tremendous energy source within the Hollow Earth. If they could harness this energy, Simmons said, they could create a weapon capable of competing with Godzilla. Lind dismissed the notion of Hollow Earth travel, but Simmons introduced a new invention: the Hollow Earth Aerial Vehicle, or HEAV. This vehicle could withstand the gravitational inversion and allow exploration of the Hollow Earth. Convinced, Lind proposed that a Titan would be able to lead them to the energy source, due to the genetic memory shared by all Titans. Lind approached Dr. Ilene Andrews at the Skull Island outpost and proposed a mission to the Hollow Earth with Kong. Though Andrews was against the idea at first, she eventually agreed on the condition that she was in charge of Kong.
En route to the entrance point in Antarctica, the fleet transporting Kong was attacked by Godzilla, who nearly killed the colossal ape before the rest of the fleet shut off its power and convinced him to leave. Kong was airlifted the rest of the way, and finally deposited near the entrance point in Antarctica. Jia, the orphaned Iwi girl with whom Kong communicated, tried to convince him to enter the Hollow Earth, but he hesitated. Only after Jia mentioned the possibility of his family being down there did Kong make his way into it. Monarch and Apex pursued Kong inside the HEAVs, and followed him through a vortex that released them into the Hollow Earth. They followed Kong across the terrain before one HEAV was destroyed by a Warbat. Another Warbat flew toward another HEAV before Kong caught it by the tail and fatally slammed it on the ground. The other Warbat constricted its body around Kong, but a HEAV forced it to release him by firing missiles at it. Kong promptly overpowered and killed the Warbat. Kong continued traversing the terrain until he came to a cliff, then leaped across to another peak. Kong came upon a huge temple-like structure, which bore the handprint of his species on the door. Kong placed his hand over it and pushed the door open, leading into a massive chamber. Kong roared into the chamber, but his roar echoed unanswered. Kong found a giant axe lodged into the skull of a fallen Titan. He then sat on a massive throne, after which the expedition members disembarked from their HEAVs. When the blade of Kong's axe began to glow blue, he placed it into an indentation on the ground which caused the glow to spread: they had found the energy source. Apex released a drone to harvest the energy, much to Monarch's displeasure. Apex's Maia Simmons had the Monarch members held at gunpoint while the drone harvested the energy and uploaded the data to Apex headquarters in Hong Kong.
The chamber suddenly began to shake, causing the Hellhawks roosting on the ceiling to flock down and attack. Maia and the Apex guards escaped in a HEAV, while Lind, Andrews, and Jia were cornered by a Hellhawk. Godzilla's atomic breath then burst through the ground, blasting the Hellhawk aside and allowing the three to reach the HEAV. Kong approached the breach in the ground, but was fired upon by Maia's HEAV. He caught the HEAV in his hand and proceeded to crush and destroy it. Godzilla roared through the tunnel he had opened with his atomic breath, and Kong answered on the other side. He grabbed his axe once again and jumped into the opening, climbing his way to Hong Kong to face Godzilla once more.
After Godzilla and Kong had defeated Mechagodzilla, Kong was returned to the Hollow Earth to live in peace. Lind, Andrews, and Jia watched Kong from a monitoring station as he passed by on his morning walk. Kong signed the word "home" to Jia before swinging himself onto a cliff, where he beat his chest and roared triumphantly.
- Kong: Skull Island - The Official Movie Novelization (2017) [mentioned]
- Godzilla: King of the Monsters - The Official Movie Novelization (2019)
- Godzilla vs. Kong: The Official Movie Novelization (2021)
When Godzilla returned to the site of his lair within the Hollow Earth, he was attacked by the fish-like Genitor and its swarm. He recognized the creatures as coming from the "deep hollows" after Serizawa's nuclear weapon opened a passage deeper into the Hollow Earth. Godzilla killed Genitor and ensured its swarm would never return, then continued searching the world for a new lair. He eventually came upon one of his old lairs within the Hollow Earth, from which he had been driven by a "rival" long ago. He was immediately attacked by the serpentine Tiamat upon reaching it, but managed to make her retreat by bringing the battle onto solid ground. Godzilla walked through his lair, passing by ancient statues and carvings of himself and other members of the Titanus Gojira race. Godzilla recognized that there was once another rival here besides Tiamat, only to see the skull of a deceased member of the Titanus Kong species. Godzilla then decided to call the other Titans back to their ancient rest before he could finally rest himself.
Camazotz, the "King of the Deep," was roused from his slumber within the Hollow Earth in 2019 by King Ghidorah, attacking San Diego along with his hell swarm. The bat-like Titan later returned to the Hollow Earth under Skull Island, where Monarch under the direction of Houston Brooks was attempting to organize an expedition through the vile vortex and into the Hollow Earth. In the meantime, a storm generated by Ghidorah had made its way to the island and combined with the perpetual storm cell surrounding the island, plunging it into darkness. Brooks realized too late that this was part of an Iwi prophecy which warned that once Skull Island was shrouded in darkness, Camazotz would come to claim his new kingdom. Camazotz burst from underground near where Monarch was drilling into the Hollow Earth and immediately set his sights on Kong. A team of fighter pilots flew into battle to assist Kong against Camazotz and his hell swarm. While Kong seemed outmatched, one of the pilots managed to disorient Camazotz by performing a sonic boom in front of his face. Kong took the opportunity to pummel his foe, then punched him back into the Hollow Earth from whence he came.
- King Kong
- Genitor (deceased)
- Genitor swarm (deceased)
- Hell swarm
- The Hollow Earth is a real hypothesis, stating that the Earth is entirely hollow or has an inner space, though it has long been discredited.
This is a list of references for Hollow Earth. These citations are used to identify the reliable sources on which this article is based. These references appear inside articles in the form of superscript numbers, which look like this: 
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