Chris Conner and Mark Barton jump onto mud-specked mountain bikes and pedal down a dirt road so overgrown with weeds it seems forgotten by man. "Get ready," says Barton, a lanky, six-foot-four 63-year-old who moves as if he were in his 30s. "Last time we did this, I ran right over a water moccasin."

Conner, a compact 50-year-old with a drawl that seems more military than Southern, pedals alongside. He enlisted in the Army at age 17 and served in Bosnia, the Gulf War, and Afghanistan. "This area we nicknamed Creepy Hollow," he says over the rattle of the bikes, "and there's an area deeper in we call the Thunderdome."

Over the past three years, they've taken more than 50 rides and hikes into the Green Swamp, an 875-square-mile protected area that forms a massive uncivilized blob on the map between Orlando and Tampa. But they've never spotted another human being.

They have, however, encountered the inexplicable. "Last time we were out — I'm not kidding you — we heard a female," Conner says.

Barton adds, "They want to get close to you is what we think, because they're familiar with us. They have a great curiosity."

The "they" Conner and Barton refer to are skunk apes, Florida's slender, hairy, and pungently scented seven-foot-tall version of the legendary Bigfoot, also known as Sasquatch. Conner claims he and his sister as children saw one when they were playing near the swamp in an area that later became a subdivision. The image of the huge creature loping along a line of banana trees and into the untamed forest has haunted him for decades.

After watching the show Finding Bigfoot on Animal Planet four years ago, Conner got the itch (he considers the skunk ape and Bigfoot to be variations of the same species). He and Barton worked together in the IT department of a nearby company in Lakeland but didn't know each other well. When Barton's terminally ill wife of 38 years passed away, Conner became more than a co-worker. "I said, 'Hey, man, you're gonna need to stay busy, dude. Just find a big hobby.' And that's how it started," Conner says.

Barton, who also pastors at an independent church, agrees: "I kinda did it as therapy, you know, not to sit at home and brood." They never intended the hobby to carry on for three years, to lead to a YouTube channel, or to suck them inexorably into what they call "the rabbit hole."

But the mysteries they've experienced in these swamps changed everything. Most weekends they enter the wilderness, hack through brush with machetes, and employ audio gear, heat-sensing FLIR cameras, and GoPros to document their quest. They've cut more than 140 videos for their YouTube channel — the Trail to Bigfoot — and a recent clip, titled "The Eyes of Bigfoot," has garnered more than 31,000 views. They have fans from as far away as New Zealand and China.

United Kingdom viewers are particularly jealous. "They wish they could do stuff like this," Conner says. Not only do they lack a Bigfoot legacy, but they also have no forest as impenetrable as the Green Swamp.

And though Conner and Barton make no money doing this, they're part of a thriving Bigfoot subculture that has turned into a cottage industry, with a proliferation of hundreds of websites, YouTube videos, books, T-shirts, conferences, $300 expeditions to "Squatchy" haunts in Oregon and Vermont, and personalities vying for TV gigs.

But as drones and trail cams give humans near-omniscience, as Florida's voracious human population spills into every open space, this once-wild state has become less wild — which raises the question:

Is this the last great gasp of the mythical skunk ape?

To Conner and Barton, it sure seems that way. After nearly three miles on the dirt road, they dismount by a small creek and prepare to bushwhack their way into the Thunderdome. "We're heading down the rabbit hole," Conner says with a grin. Then things get weirder.

Bigfooting, the verb that Conner and Barton use to describe what they do, is part of a field known as cryptozoology, or the study of and search for animals whose existence is disputed or unverified. Think of the Loch Ness monster, the abominable snowman, and the chupacabra.

Cryptozoologists scored a win in 1901 with the discovery of the much-rumored okapi, a sort of minigiraffe with stripes and a short neck that lives in the African jungle where Joseph Conrad set Heart of Darkness. But none of the more sensational animals on the cryptozoologist checklist has been verified by science — no DNA, skeletal evidence, or poop. Yet there are still undiscovered freaky creatures on the planet: a World Wildlife Fund project searching the Mekong region of Thailand recently identified 163 new species, including a large fanged frog that eats birds. And just last month, scientists verified a whale species that had previously been only a rumor, when a body washed up in a remote area of the Bering Sea.

Cryptozoologists sometimes employ anecdotal evidence, which doesn't add up to proof but can inspire belief. Thus, there has been a proliferation of TV shows such as Monster Quest (History Channel), Beast Hunter (National Geographic), Weird Travels (Travel Channel), and Monsters and Mysteries in America (Discovery Channel). There's even a street artist named Bigfoot One who sells tees at Urban Outfitters.

Versions of Bigfoot, a tall, hairy creature that is theoretically a hominid, are common all over the globe. There are the yeti in Nepal, the mapinguary in Brazil, the yeren in China, the almas in Kazakhstan, and the higabon in Japan. Gigantopithecus, a ten-foot-tall, 1,000-pound distant relative of the orangutan that lived in ancient Southeast Asia, is often cited as a potential evolutionary link — but fossil records indicate they died off around 100,000 years ago during a climate shift. Scientists also believe gigantopithecus was likely not a biped and would therefore have hip biomechanics that are different from a skunk apes's.

The watershed moment in North American belief in Bigfoot is the now-iconic Patterson-Gimlin film, shot in northern California in 1967. It shows a big, stocky, humanlike beast striding through a forest clearing. Most shocking is the muscularity of the animal's legs and butt — it does not look to be a normal man in a floppy gorilla suit; it has a solid and almost graceful appearance.

The film launched a Bigfoot fever that took hold in 1970s Florida — so much so that the Yeti Newsletter began a bimonthly publication in St. Augustine. Here are some highlights:

• In 1973, a mother skunk ape and her three-foot-tall baby scared a child off a tricycle in Brooksville, north of Tampa. When the human family ran from the house, they witnessed the baby skunk ape turning the wheel of the upturned trike. The baby then returned to its mother, which stood seven feet tall. The humans noted an "unusual pungent odor" before the skunk apes hurried into the woods.

• In 1974, a skunk ape was struck at night by a car on the western fringe of Hollywood, denting the fender and leaving strands of hair. The creature limped into the brush. An officer on scene didn't follow, but there were fires set by locals, a helicopter search, and random firing of weapons in hopes of bagging the creature.

• In the Bahamas, a tribe of two-foot-tall miniyetis, called yahus, was spotted on Lubbers Island. They apparently had four eyes, a pair in front and back; their feet faced backward; and they played absolutely lovely music on homemade instruments. An old man claimed to have been kidnapped by the yahus for three days as a boy and fed bananas. One writer postulated they might be a remnant of the lost continent of Atlantis.

And then the internet happened. Like-minded folks interested in any form of animal could validate one another, argue, and form a cocoon of belief. YouTube is a breeding ground for skunk ape-hawking attention seekers, and the results run the gamut from sleazy clickbait to disturbingly realistic. One clip called "Florida Skunk Ape Caught on Game Camera?" shows random photos of gardens, a trail camera, and then, sulking behind a tree, an animal that is clearly a gorilla. Others include the larger-than-life skunk ape personality named Tim Fasano, who claims to have been in talks with Animal Planet in 2011 and who was exposed by a rival who said he was also running a blog that viciously attacked the claims of skunk-apers. Apparently, there were death threats, and Fasano quit the Bigfooting game.

Still, other YouTube clips are chillingly convincing. One video from 2013 shows the rear view of what looks like a gorilla patiently ripping open the bottom of a cypress tree. When the animal stands up, it becomes clear that it's huge, tall, long-legged, and of no species currently known to science. The cameraman flees after shooting footage of the beast looking at something glimmering in its hand. (Furious commenters called him a p***y.)

Today the most famous skunk ape hunter in Florida is Dave Shealy, proprietor of Skunk Ape Headquarters, a gift shop, airboat, and adventure tour operation on the Tamiami Trail. Shealy has appeared on the Discovery Channel, Unsolved Mysteries, and The Daily Show. He says that his family has been in the area since the 1800s and that skunk apes have been observed for hundreds of years. A Miccosukee tribal elder told him that when Native American forefathers were first pushed into the Everglades by war, they located a family of skunk apes living on a hammock and sent an emissary to try to communicate. "They thought that if they had these huge guys on their side, it would be a force to be reckoned with," Shealy says. Unfortunately, the communication efforts failed. "They just looked at him like they didn't understand, and they walked off."

Shealy claims to have had three skunk ape encounters, and filmed one in 2000. Though the video is quite grainy and the beast moves with questionable biomechanics, Shealy says it's the best skunk ape footage ever shot. "It far exceeds most anything that Patterson-Gimlin did out in California. And most of the videos coming out of Florida right now are just a blob. I don't know why it hasn't gotten more attention."

Shealy says of the skeptics: "It's a lot easier to say the skunk ape doesn't exist than to do any research."

It's 9 a.m., 30 minutes and three miles into Conner and Barton's journey to the heart of the Green Swamp. This is where the 140-mile Withlacoochee River begins to seep from the earth. Sun slices through the canopy, illuminating diamonds on spider webs and wild grass. Conner and Barton lay their bikes on the ground and prep their gear: GoPro, audio devices, FLIR thermal-imaging camera. Machetes in hand, they leave the bikes behind and part the leafy walls of the forest, pushing through palmetto fans and stepping over dead trees and mounds of duff rooted by feral hogs. They follow a wet path along a small creek while carefully looking out for snakes and the alligator they spied last time they were here. Eventually, the underbrush gives way to a cathedral-like space where a broad sandbar has created an open glade of tall cypress trees. Barton stops and looks up as dragonflies zip through the cool, airy realm. "Welcome to the Thunderdome," he says.

The pair doesn't plan to pursue a skunk ape. They hope to pique its curiosity and provoke interaction. The idea is to simply hang out, chat calmly, and they'll come. These guys never bring firearms into the woods. "We feel if we carry weapons, they'll sense that," Conner says while Barton pans the GoPro around the perimeter of Thunderdome. "I subscribe to this: Once you're in their area, they have no choice other than to... watch you." This explains why the guys haven't used dogs to track the skunk apes. Conner also says he doesn't want a dog to get killed by a seven-foot-tall primate.

What do the skunk apes eat? "They're king of the jungle out here and eat whatever the hell they want — deer, snakes, hogs. If they wanted to harm us, they could have by now," Barton says.

Conner suggests Barton's six-foot-four build paired with his five-foot-six frame causes the creatures to read them as father and child skunk apes — less threatening than two adults.

"If you really want to meet Bigfoot, come out here at night by yourself in the middle of winter when this sandbar is dry. I won't do it. I'm scared," he adds. "I don't want one of them damn things to eat me."

In his youth, Barton, who grew up in Indiana, played street ball as opposed to high-school hoops. ("You didn't have to be as good!") He studied engineering in college and has worked in IT since the early '90s, "when it was fun," he says. He missed being drafted into the Vietnam War by a few lottery slots and watched buddies go off to war. At age 21, he married and then had three sons, none of whom are into Bigfooting. (They buy him Sasquatch T-shirts, though.) He has managed to get one of his grandsons into the swamp.

Conner grew up in Lakeland. His father would bring home UFO and Bigfoot magazines but never went out exploring. In the military, Conner was responsible for running satellite and other forms of communication. On his latest deployment in Afghanistan, he helped set up a forward operating base near the Pakistani border. Then he retired as a master sergeant. "I was lucky. The only weapon I had to carry in Afghanistan was a pistol." While stationed in Germany, Conner met his wife, who returned to the States with him and who occasionally ventures into the swamp. Both of their sons, one studying nursing and one aerospace engineering, have gone Squatching as well.

"We're not into the paranormal crap. But out here, we hear voices, stuff that says our name." Facebook

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After panning with the GoPro, Barton pulls out the FLIR and checks the forest for heat signatures that might indicate a large mammal. As he squints through the scope, he concedes that there's such a thing as having "Sasquatch on the brain... I'll be the first to admit it. You can look in the woods and see a face."

That's why he records every outing — he wants to confirm they're not crazy when they hear voices and gibberish just out of sight. Their biggest hit on the YouTube channel, a 3.5-minute video shot this past April and dubbed "The Eyes of Bigfoot," occurred when Barton heard chatter and movement. Conner swung the camera to the likely spot. In real time, they were unaware there was anything watching them, but the footage showed a curiously large, dark object behind some palmettos. When they magnified it and ran it in slow-mo, they saw what they believe is a skunk ape blinking. When they returned to the spot later, the figure was — of course — gone.

That was just one of many eerie finds. Take, for instance, that ambiguous-looking footprint much too large to be human or bear. Or the video of a sapling bent and woven together with another tree in a way that seems to require a seven-foot frame and opposable thumbs. Many Bigfooters theorize these tree alterations, seen in numerous Squatchy areas around the United States, are a form of skunk ape art — or maybe territorial marking.

In January 2015, Conner and Barton were startled by the sound of a hog being killed 50 yards away in the brush. After calling out to make sure they wouldn't get shot by a bow hunter, they found nothing there. This past January, they left a carrot bag on an abandoned fridge from a '60s logging operation. When they returned two weeks later, the carrots were gone and the bag was on the ground. The next week, the bag was gone. Six weeks later, the bag was back, hooked onto a piece of metal pried from the side of the fridge.

"No critter did that!" Conner says.

"There is something out there," Barton confirms.

"We're not into the paranormal crap," Conner says. "But out here, we hear voices, stuff that says our name. They hear us talk. It's mimicry."

Conner looks out to the thick layers of palmetto blades and continues chatting, strolling about the Thunderdome, moving in a relaxed way, then listening. The wet swamp sand bubbles under his weight. Above, the thrum of thousands of cicadas sweeps through the treetops. In the distance, a mob of crows prattles. Conner points back to the road where the bikes lie a quarter-mile away. Then he predicts that if they hear something strange, it'll be at 10 o'clock or 2 o'clock to their position. That's how the skunk apes surveil, he says — watching and playing peekaboo just out of range of vision. "They seem to be incredibly patient, beyond our understanding," says Barton, still looking through the FLIR. "We feel like they see time differently. They can sit for hours and not be seen."

Standing at the far end of the sandbar, brow damp with sweat, Conner adds, "We've been out to our areas enough to know that we can interact with them without being harmed, as long as we don't push the envelope."

After an hour in the woods, it's time to see if they can provoke a "knock" — a term Bigfooters use to describe a loud wood strike that indicates a skunk ape communication or territorial claim. Conner launches into a soothing, singsongy call-out to the creatures. "Don't be shy. You can come out." His voice fades into the maze of cypress. "We won't hurt you at all... just make a noise."

They wait in silence for about a minute, and then it sounds — like a baseball bat on a tree, about 100 yards out. "Did you hear that?! Ten o'clock," Conner says. He tries to lure it by singing coaxingly. "We heard you... Can you do that again?"

They wait again. Nothing.

A few minutes pass before Barton gets a gleam in his eye. "Should we talk about the other?" he says to Conner, who nods consent.

"We don't want to sound like we're losing our damn minds," Barton says, "because we're not." Then he relays the tale of how two weeks ago, as he entered the swamp, he encountered a tall, upright, shimmering figure. He jumped back and nearly fell over. "It was like the movie Predator," Conner says.

When Barton took another look and tried to replicate the light angle, it was gone. "I didn't see it again, but I know what I saw. I definitely know what I saw."

The shimmering does have a biological precedent. Some fish have platelets in their skin that reflect surrounding environmental hues. It makes them shiny at some angles but camouflaged and nearly invisible to predators at other angles. Conner claims many Bigfooters have seen such phenomena but won't admit it publicly. They fear not being taken seriously by academics. "How do you say the words without people going, 'All right, you guys are in too deep; you're over your head.'?"

Barton, with a grin on his face, surveys the primordial cathedral.

Conner raises an eyebrow and smirks. "You see what I mean about the rabbit hole?"

If ever there were a place that could support a secret population of large hominids that somehow remains undiscovered despite our video-obsessed 21st-century reality, it's the Green Swamp. The area's mosaic of hardwood forests, marshes, pine flatwoods, sand hills, and cypress swamps makes it biologically diverse, with 330 animal species. The four rivers that emanate from it allow animals to travel from one habitat to another. It's a feast for any apex omnivore.

How much would a skunk ape need to eat? Conner and Barton estimate the creatures weigh up to 400 pounds. A mature male black bear in Florida is about the same size. Bears gorge in the fall, foraging 18 hours a day to snarf down 20,000 calories (8.5 large cheese pizzas), but during the late spring and summer, they cruise on 5,000 calories a day (two large cheese pizzas or 20 pounds of fruit).

Given the abundance of feral hogs, armadillos, and alligators in the swamp, as well as nearby orange and banana trees, it seems a population of skunk apes might just be able to establish a steady diet.

Still more evidence of primate survivability comes from a spooky story of a wild human lurking in the Green Swamp. Locals will tell you that back in the day, authorities captured the "Green Swamp Wildman," a seven-foot-tall Korean man who'd hidden in the swamp since the Korean War. He was rumored to have an emerald in his forehead and speak an ancient Korean dialect no longer in use.

The truth of the Green Swamp Wildman is less sensational and much more tragic. The Orlando Sentinel reported in 1991 that he was actually a homesick Taiwanese sailor named Hu Tu-Mei who had been hospitalized after a violent episode in Tampa. The man escaped from the hospital and fled, making his way to the Green Swamp and surviving for eight months on armadillos and corn left out for wild turkeys.

"Skeptics can say a lot of things, but most skeptics don't go out there and experience it themselves." Facebook

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Eventually, he was captured, but before he could be sent back to Taiwan, he hanged himself in his holding cell. Whether he was ever mistaken for a skunk ape is unclear, but some say the Green Swamp is still haunted. The same Orlando Sentinel story reported that "hunters lost in the Green Swamp for just a few days have come out babbling to rescuers." About what? A creature they'd seen? A shimmering presence? It's unclear.

Of course, skeptics are legion. In fact, there's a whole subculture. Sharon Hill is a geologist and editor of DoubtfulNews.com, a website where she pulls the rug out from under skunk ape believers. She also casts a critical eye on the perils of scam faith healers, astrologers, and psychics. "I've written for some [Bigfoot/skunk ape] blogs, and, boy, they don't want me around," she says. "I've been booted out of a couple forums. They just don't want to be questioned."

Hill contends a lot of Bigfooters use predictable arguments that don't add up to actual evidence, and engage in what she calls "anomaly hunting."

"You'll notice that they look for things in the environment (tree configurations, sounds, smells, dark shapes in the distance) and consider them anomalies. Then they put their own creative interpretation onto them. They don't seem to consider normal explanations very much: No one observed an animal making that tree arch; a storm could have done it. Implausible? Yes, but not as implausible as an unknown large intelligent ape avoiding human contact in a regularly visited landscape."

Hill watched a few of the Conner-Barton videos. "I found them kind of boring."

As for the sense that "there's something out there" in the swamp, Hill says, "I don't doubt that it's unnerving to be out there... but to say it's something that we haven't discovered yet, there's just no rationale for that... They have to eat, and they have to poop, and they have to leave tracks, and they have to leave hair and DNA and bodies. And we're just not finding that."

Hill was once a believer. "Ever since I was little, I liked to read about monster stories and paranormal stuff. But after I got trained in science, you know, you sort of take a different view of the world."

She doesn't think most Bigfooters are lying. "[Many] are just looking for something interesting in life. Maybe they don't love their regular job, and they like to get out on the weekends and do something more exciting."

How would she feel if a skunk ape were verified? "That would be so great. That would be amazing and exciting! I want it to be true; I'm just not convinced by the evidence — yet. Bring me a body, bring me DNA, and I'll be convinced."

Conner, though, has an explanation for the lack of bodies: "They go out there and recover their dead. They're that intelligent... Skeptics can say a lot of things, but most skeptics don't go out there and experience it themselves. Just because you don't lay eyes on something doesn't mean there's nothing there. If I can yell out into the woods and get a knock back, that's a pattern. There's conjecture, of course. But it does not mean what you're experiencing is make-believe."

"I've accepted that no matter what kind of evidence you have, it'll never be enough for some people," Barton says.

"Unless you're sitting down having beer and pizza with a skunk ape and you get that kind of footage, it's always gonna be conjecture and subjective," Conner adds.

Both believe that all the skepticism has scared off more rigorous examination. "We have spoken to academics who say, 'I'm not allowed to say I'm out doing this'... [They] basically risk tenure and the ability to be considered credible," Conner says.

Conner and Barton hike the quarter-mile out of the Thunderdome, mount their bikes, and begin the journey back to civilization — a war veteran and a widower pedaling their way through overgrown grass. The sun is up and it's intensely hot; Conner has to take a break — the heat has him seeing stars. Though it can be brutal out here, the process is a treasure to these guys. "As a man, it's therapeutic," Barton muses. "As a man who's recently lost his wife, it's therapeutic. It bonds men. You don't have that bonding outside the Army, but you feel like you should. I know that if something happened to me, Chris is gonna take care of me. And if something happens to Chris, I'll drag his ass out."

A Cooper's hawk cries overhead. "Most men don't have close relationships with other men," Barton says. "I do. I'm older now. I'm not afraid to say I need a friend who would not leave my ass in the woods."

Sebastian Junger's recent book Tribe: On Homecoming and Belonging and his related TED Talk posit that PTSD and the troubles vets have upon landing in civilian life are more than a stress reaction to bullets and bombs; they are about a loss of meaning. He talks of a vet who misses war — not the killing, but the brotherhood. "Think about a bond like that and how good that would feel," Junger says in his TED Talk. "Then they are home, not knowing who they can count on, not knowing who loves them, who they can love, not knowing exactly what anyone they know would do for them if it came down to it. That is terrifying."

An hour later, Conner and Barton, soaked in sweat, take a seat at their favorite barbecue joint, the Red Top Pit Stop. It's the kind of place that loops college football reruns in the offseason and serves pulled pork and ribs you'll gladly travel for. The two reminisce about the knock, the screaming pig, the gibberish, the shimmering beast. They have considered quitting the Squatching game, but when they mentioned it in a video, their YouTube followers protested.

Barton pauses from his pulled pork and coleslaw. "Humans think we know everything. We're very arrogant as a culture. So the very fact that there could be something that we don't understand, that's a mystery, I think it's awesome. I like mystery."

Conner smiles. "I think the mystery is important to our heritage," he says. "The history of America — it's America's original myth." He raises that eyebrow again. "Part of me doesn't ever want it to be discovered."