The Cryptoterrestrial Hypothesis: A Plain English Exploration of Hidden Earthly Explanations for UAP

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Introduction: A Strange Possibility Worth Considering

Unidentified Anomalous Phenomena—commonly called UAPs, once known as UFOs—remain one of the greatest unsolved mysteries of our time. Across centuries and cultures, people have reported strange objects in the skies, lights that dance across oceans, or craft that seem to defy the known laws of physics. For most of modern history, such reports were dismissed as tricks of the eye, atmospheric illusions, or hoaxes. But in recent years, governments and scientists alike have been forced to take them more seriously.

Traditionally, there have been two main explanations for UAPs. The first is that they are conventional terrestrial phenomena—new aircraft, drones, balloons, secret military projects, or natural events misunderstood by observers. The second is the extraterrestrial hypothesis—that they are visitors from other star systems, civilizations far beyond our own who have somehow achieved the technological feat of interstellar travel.

But there is a third possibility, one that sits outside conventional debate: that UAPs are not from space at all, but from here on Earth. This is called the Cryptoterrestrial Hypothesis (CTH). It suggests that non-human intelligences—whether hidden civilizations, breakaway groups of humans, or another intelligent species—may already be present on or beneath the Earth, coexisting with us in secret.

The authors of the paper—Tim Lomas, Brendan Case, and Michael Masters—are clear about their position. They do not believe CTH is the most likely explanation. In fact, they say outright that it is probably false. But they also stress that science should not reject it out of hand. Their argument is about openness: the idea that, given how strange and puzzling UAPs are, every possibility should be put on the table and tested.

This essay expands on their paper in plain English, tracing the history of UAPs, reviewing what governments and scientists know, and exploring how hidden earthly intelligences might fit into the puzzle.

The Rise of the UAP Question

From Ancient Reports to Modern Sightings

Stories of strange lights and sky-borne objects stretch deep into human history. Ancient chronicles describe fiery chariots in the heavens, mysterious wheels of light, and beings descending from above. Medieval texts tell of aerial battles, glowing spheres, and visitors whose origins were left unstated.

In the modern era, as aviation advanced, sightings became more frequent and were soon labeled “flying saucers.” The U.S. Air Force’s Project Blue Book investigated thousands of cases between 1952 and 1969, dismissing most as explainable but quietly acknowledging that a significant minority defied conventional understanding.

As technology advanced, so too did the reports. Objects were tracked not only by human eyes but also by radar and sensors. Multiple witnesses, including trained pilots, described craft that moved at extreme speeds, changed direction instantly, or hovered silently in ways no known aircraft could.

2017 and the New Era

The conversation around UAP changed dramatically in December 2017, when The New York Times published footage from U.S. Navy pilots. The videos, later confirmed as authentic by the Pentagon, showed small white objects—nicknamed “Tic-Tacs”—maneuvering in ways beyond current technology: dropping from 60,000 feet to sea level in seconds, or accelerating as if “shot from a rifle.”

This revelation forced a reevaluation. Suddenly, UAPs were not fringe or laughable. They were a matter of national security and scientific curiosity. The U.S. Department of Defense established a UAP Task Force, later renamed the All-domain Anomaly Resolution Office (AARO), to study them.

Though cautious, AARO admitted that out of hundreds of cases, a handful—between 2 and 5 percent—appeared genuinely anomalous. They exhibited “concerning performance characteristics” such as high speeds, instantaneous acceleration, or transmedium travel (moving seamlessly between air, water, and possibly solid ground).

Government Secrecy and Whistleblowers

Alongside these admissions came allegations of secrecy. Former intelligence officer David Grusch claimed under oath to Congress in 2023 that the U.S. government had long been recovering crashed UAP and attempting to reverse-engineer their technology. Other officials, including retired military officers, have publicly supported his claims.

While unproven, these testimonies have been taken seriously enough to spark proposed legislation requiring disclosure of UAP-related materials. Even top senators like Chuck Schumer argued that the public has a right to know whether non-human intelligences are interacting with Earth.

The question remains: What are UAPs? If they are not misidentified planes or balloons, and if extraterrestrial travel is as difficult as scientists believe, perhaps the explanation lies closer to home.

Ultraterrestrial Theories: Beyond Aliens

When most people think of UAP, they imagine aliens visiting Earth from distant stars. But researchers have proposed other, less conventional possibilities, grouped under the label ultraterrestrial hypotheses. These suggest UAP may not be “alien” in the usual sense but rather forms of intelligence already intertwined with Earth in unusual ways.

Some examples include:

Interdimensional beings: entities existing in dimensions beyond our usual perception of space and time.
Extratempestrials: time travelers, possibly future humans studying their own past.
Cryptoterrestrials: hidden civilizations or species living secretly on Earth or nearby (underground, undersea, or even among us).

The cryptoterrestrial idea is the focus of this essay.

The Cryptoterrestrial Hypothesis (CTH)

The Basic Idea

The CTH proposes that UAP are linked to intelligences already based on Earth. They may not come from the stars but instead from concealed habitats beneath our feet, under the oceans, or hidden in remote places. Some versions even suggest they walk among us, indistinguishable from humans.

This hypothesis is not widely accepted. Most scientists view it as speculative at best. But the authors argue that the strange nature of UAP—especially underwater sightings and underground associations—means CTH deserves at least some consideration.

Why the Idea Persists

There are two major empirical puzzles that lend weight to CTH:

Unidentified Submersible Objects (USOs) – Many credible reports describe craft moving at impossible speeds underwater, without visible propulsion. They often appear to emerge from the ocean rather than simply enter it. The 2004 USS Nimitz encounter, for example, involved a “Tic-Tac” linked to a disturbance just below the water’s surface.
Underground and Volcanic Sightings – Some UAP seem to vanish into volcanoes or caves. Mexico’s Popocatepetl volcano is a noted hotspot for such sightings. Observers speculate that these might serve as portals, bases, or hiding places for non-human intelligences.

Taken together, these raise the question: could UAP originate not from space but from Earth’s hidden realms?

Four Versions of CTH

The authors outline four main interpretations of the hypothesis.

1. Survivors of Ancient Human Civilizations

Perhaps Earth once hosted advanced civilizations—like the legendary Atlantis—that developed technology and then went into hiding after disasters. Their descendants may still survive in hidden enclaves.

Archaeology shows that sophisticated societies can vanish almost without trace. The Indus Valley civilization, for instance, flourished for centuries but was unknown until rediscovered in the 1920s. Could there have been others, more advanced, whose remains we have not yet found?

2. Non-Human Earth Species

Earth’s evolutionary history is full of surprises. Many hominin species—Homo erectus, Homo floresiensis, Homo naledi—once lived alongside modern humans. It is not impossible that another intelligent lineage evolved, perhaps adapted to underground or aquatic life, and chose to remain hidden.

Such beings might explain reports of UAP occupants that look humanoid but not quite human.

3. Breakaway Human Civilizations

Another version suggests that at some point, a group of humans separated from mainstream society and advanced independently. This “breakaway civilization” might have developed secret technologies, choosing seclusion over participation in global history.

If true, their motives remain mysterious—survival, avoidance of conflict, or a desire for independence.

4. Disguised Beings Among Us

The most speculative strand suggests that cryptoterrestrials could live within human society itself, disguised or naturally similar enough to blend in. Legends of “hidden people,” fairies, djinn, or shapeshifters may reflect folk memories of such encounters.

Former officials have even hinted that non-human species might be “walking among us” unnoticed.

Cultural and Historical Roots

The idea of hidden civilizations has deep roots in myth, literature, and folklore.

Mythology: Many cultures tell of underground or hidden peoples—elves in Norse lore, djinn in Islamic tradition, the Tuatha Dé Danann in Ireland, or Nagas in Hindu mythology. These beings often interact with humans mysteriously, sometimes helping, sometimes tricking.
Literature: Jules Verne’s Journey to the Center of the Earth imagined vast subterranean worlds.
20th century science fiction: The “Shaver Mystery” of the 1940s claimed ancient underground races still lived beneath Earth. While discredited, it influenced UFO lore.
Modern thinkers: Writers like John Keel and Mac Tonnies revived the idea, suggesting cryptoterrestrials are a more plausible explanation than interstellar visitors.

Such stories may not be literal evidence, but they show how humans across eras have intuited the possibility of hidden neighbors.

Why CTH May Fit UAP Better Than ET

While extraterrestrial explanations capture the imagination, CTH offers some advantages:

Proximity: There is no need to solve the immense challenge of interstellar travel.
Human-like forms: Reported beings often resemble humans, which could make sense if they share evolutionary roots with us.
Interest in Earth: UAP appear especially concerned with nuclear sites and natural ecosystems—behavior consistent with beings who also depend on Earth for survival.

Limits of Our Knowledge

Our knowledge of Earth’s history is fragmentary.

Fossil record gaps: We have evidence for only a fraction of extinct species. Some estimates suggest 95% of primate lineages are lost to time.
Lost civilizations: Major cultures like the Indus Valley remained unknown for millennia. Others may still lie undiscovered.
Unexpected discoveries: Finds like Homo naledi, who buried their dead and may have created art, show that intelligence and culture appeared earlier and more widely than once thought.

Given these gaps, it is at least possible that something important has been overlooked.

The Scientific Challenge

Science advances by testing bold ideas. Many discoveries once thought absurd—continental drift, germs as causes of disease, quantum physics—turned out true. The authors argue that CTH, however unlikely, should be placed in this same spirit of inquiry.

They call for epistemic humility: acknowledging the limits of current knowledge and resisting the urge to dismiss unconventional ideas outright. Instead, they advocate systematic investigation of UAP reports, especially underwater and underground cases, using the best available methods.

Conclusion: Keeping an Open Mind

The cryptoterrestrial hypothesis is not a claim that hidden civilizations definitely exist. Rather, it is a reminder that the universe—and even our own planet—still holds mysteries. UAP are real, puzzling phenomena. While many can be explained as ordinary objects, a persistent core defies explanation.

In exploring possibilities, extraterrestrial visitors are often assumed to be the only radical option. But perhaps the answer lies closer: in our oceans, in deep caverns, or even among us.

The authors stress that CTH is unlikely, but they believe the responsible scientific attitude is not dismissal but investigation. Only through openness, patience, and rigorous inquiry will humanity come closer to solving the riddle of UAPs—and perhaps discovering whether we truly share Earth with others.

Would you like me to also structure this into a polished PDF report (with section headers, diagrams comparing the four CTH variants, and timelines of UAP events) so that you can use it as a reference document?