One of the 20th century’s greatest Fortean investigators was a man by the name of Ivan T. Sanderson. Best known for his contributions to cryptozoology, a word he’s credited with coining, Sanderson was also a pioneer in the subculture of USO (Unidentified Submersible Object) research. He had many monikers for the unknown objects seen entering and exiting bodies of water, referring to them as UAOs (Unidentified Aquatic Objects) or “underwater babies” (his adorable term for craft observed interacting with freshwater). Regardless of the label, putting a name to the soggy phenomenon doesn’t do justice to its nuances. In light of a growing number of witness reports and verified Navy videos depicting transmedium craft operating above and beneath the ocean, it’s a fitting time to evaluate the USO enigma from a historical perspective.
In 1970, Ivan Sanderson summarized his views on USOs in a book with a title that left nothing to the imagination. Invisible Residents: A disquisition upon certain matters maritime, and the possibility of intelligent life under the waters of this earth, revealed that a startling number of UFO sightings (more than 50%), “have occurred over, coming from, going away over, or plunging into or coming out of water.”
Some of this can be explained by the simple fact that water is everywhere. A 2011 study published by the Public Library of Science revealed that “over 50% of the world's population lives closer than 3 km to a surface freshwater body, and only 10% of the population lives further than 10 km away.” While this fact makes the chances of someone spotting a UFO near H2O a predictable correlation, the increased odds have yet to translate into an increased understanding of their origins, capabilities or intentions.
Sanderson wasn’t the only investigator of the era to note the prevalence of waterlogged cases— ufology’s elite were also puzzled by the frequent occurrences. In a 1977 interview with Oui (a men’s magazine similar to Playboy), Project Blue Book astronomer, Dr. J. Allen Hynek, highlighted the bizarre relationship between UFOs and the drink: “There also seem to be correlations with power lines, military installations, and — oddly enough — small bodies of water. I can’t even speculate about the last one.”
Luckily, Sanderson didn’t mind indulging in speculation—“merely as an intellectual exercise, of course!” He suggested that UAOs might not be piloted by otherworldly beings. Instead, perhaps they were operated by Earth’s own “invisible residents”—an ancient civilization living within the hydrosphere. He theorized about the existence of an advanced aqueous culture inhabiting the planet’s watery depths. These Other Intelligences (OINTS) would conceivably hold an advantage over their landlubber counterparts by choosing to remain in their original habitat below the waves (where life on Earth began). Instead of wasting time adapting to the surface, undersea OINTS would have a massive “head start” in developing technologies far more advanced than our own. It helps that the earth is mostly covered with water, since the combined volume of the oceans, lakes and rivers would provide an enormous habitable zone in which our aquatic neighbors could flourish.
Sanderson guessed that water-dwelling OINTS would likely hide themselves in bases at the bottoms of the oceans in order to avoid detection for extended periods of time. He characterized the ocean floor as “an open invitation for residence…for all manner of things.” When considering the vastness of the seascape, it’s reasonable to think that intelligent entities living within the deepest abyssal waters would prove hard to locate, despite our best naval efforts.
Adding to these conjectures—if USOs were controlled by an aqua-amenable society, then the end of the last ice age and resulting increase in sea level would’ve provided even more room for them to roam and expand. Instead of a global flood spelling the end for an advanced civilization, the deluge would’ve amounted to an underwater land-grab.
‘Invisible residents’ controlling transmedium vehicles soon became the prime suspects in the mysterious disappearances of ships, planes and people happening around the area of ocean known as the Bermuda Triangle. In his 1974 book on this infamous stretch of water off the coast of Florida, researcher Charles Berlitz commented on the proliferation of water-UFOs, implying a connection with the strange maritime vanishings: “They have been seen under the clear waters as well as in the skies, and going from the sky to the sea and from the sea to the sky, by numerous reliable observers.”
Berlitz’s book includes a discussion with fellow Fortean-enthusiast, Dr. J. Manson Valentine. Valentine delivered an anecdote of a noteworthy USO sighting from April 1973 by the captain of a boat traveling the turquoise waters on the northern boundary of the Bermuda Triangle. The credible witness had two encounters with a “grey-white object, smooth and shaped...like a fat cigar with rounded ends.” As it “rushed past the bow of his boat underwater” he determined its size to be an astounding “150 to 200 feet long.”
The captain’s physical description sounds a lot like the recent U.S. Navy pilot reports of an “elongated egg,” or “Tic Tac”-shaped UFO observed zipping across the surface of the oceans.
To be fair, it also sounds a lot like most military submarines.
Both Berlitz and Sanderson dedicated space in their books to a convincing 1963 incident that reportedly occurred off the coast of Puerto Rico. Few accounts of the tale made it to print despite the extent of the purported interaction. As the story goes, during a preplanned naval exercise involving multiple small vessels, submarines, air support, and (depending on the source) one battleship, a sonar operator was alerted to the presence of an unknown “high-speed submersible.” The anomalous object was clocked at 150 knots (173 mph) while operating at depths below five miles—numbers well beyond the capabilities of any underwater craft in existence. Some versions allege that the fleet tracked the USO for four days, obtaining solid sonar pings across multiple ships. Despite the promising narrative, no visual confirmation was reported and no official acknowledgments have been produced.
Sanderson attributed this harrowing report to two earlier sources: an article titled “U.F.O.’s at 450 Fathoms” from the March 1966 issue of Man’s Illustrated, and a chapter contained within the book Hydrospace (1964) by highly-respected technical author, Martin Caidin. Caidin’s retelling identified the convoy of ships as civilian research vessels instead of a military flotilla, but the main details and location were the same. While his book focused primarily on scientific aspects of “the fabulous World Beneath the Seas,” Caidin didn’t mince words with his bold conclusion about the anomalous 1963 encounter:
“Deep, deep down, five miles deep into the realm of hydrospace, there existed a form of life of which we had not the slightest conception, and which must be possessed of physical strength and driving energy that is beyond the understanding, or even the imagination, of man.”
Invisible Residents presented a wide-range of interesting cases to support Sanderson’s UAO musings. One alarming 1958 episode included “an undersea ‘object’ which refused to identify itself...spotted by Navy pilots.” An Associated Press article about the incident was published with additional details in the Evening Star on March 19, 1958. It reported that the Navy “pounced with destroyers and planes” after detecting an “unidentified underwater object” during routine training exercises in the Pacific Ocean near Bodega Bay, California. The Navy deployed 11 destroyers along with a complement of aircraft in search of the object. Despite the effort, “the results of the investigation were negative.”
The specifics of this event sound eerily similar to UFO incursions documented in the same area by Navy crewmen in recent decades. A leaked 2019 video from the bridge of the USS Omaha captured footage of an unidentified craft cruising over the surface of the Pacific Ocean moments before it dove into the waves and disappeared. Navy submarines sent to retrieve the object came up empty handed. In 1970, Sanderson presciently reasoned that the beings behind USO activity might be “so far in advance of us technically that we would never have even noticed it until we started to develop a few really sensitive gadgets.” Indeed, the latest rash of Navy videos are mostly available courtesy of cutting-edge infrared technology, high-tech sensors and state-of-the-art detection systems.
Another researcher advocating that an intelligent subterranean race might be responsible for USOs was British ufologist, Brinsley Le Poer Trench. In his book, Secret of the Ages: UFOs from Inside the Earth (1974), he contended the reason people saw so many USOs coming from the oceans was because that’s where the hollow-earth-dwelling OINTS entered their “cavern world inside the earth.”
Trench pulled from disparate sources to demonstrate his belief that Earth’s interior consists of countless tunnels constructed by a lost group of extraterrestrial “Atlanteans.” He suggested that this ancient society arrived on Earth from another planet eons ago and later went underground to survive a cataclysmic disaster. According to his thesis, alien-Atlanteans still reside beneath the surface and occasionally venture topside in their advanced USO technology.
In the wake of speculation built upon Sanderson’s theories about USOs and invisible earth-residents, an entirely different interpretation emerged from George Johnson and Don Tanner in their book, The Bible and the Bermuda Triangle (1976). While they agreed that a real phenomenon was taking place in the world’s oceans, they objected to the idea that unidentified craft were occupied by citizens of an ancient ‘Earthly’ culture. Instead, they accused Lucifer and his fallen angels of having their claws in the mix—believing the strange objects seen by eyewitnesses were physical manifestations of “diabolic entities.”
The authors conceded that “Sanderson’s theory of a present underwater civilization and speculation that UFOs are coming from that area may seem incredible,” but they go on to insist that “there is biblical evidence that a world or civilization of a different order exists beneath the sea, and some of its visitors have a profound influence on our world.” The book placed an entrance to Hell in the vicinity of the Bermuda Triangle (aka Devil’s Triangle) and claimed it was no coincidence that the deepest parts of the Atlantic Ocean were located within its borders.
As contemporary unmanned underwater vehicles (UUVs) grow more sophisticated, and news of Chinese “flying submarine drones” prove the reality of transmedium machines, a worldly explanation for USO encounters seems highly plausible. Yet the tidal wave of pre-1970 reports describing strange aquatic craft can’t be easily written-off as cases of human technology. Even though they go by different acronyms, the same questions posed about the nature of unidentified flying objects should apply to the submersible variety.
Fifty years later, Sanderson’s description of the mysterious aqueous phenomenon still remains the most appropriate: “When it comes to something like underwater UAOs, we find that nobody really has a clue as to what is going on.”