“If you’re going to be dumb, you better be tough,” laughs our guide, Luis Zaiden, after concluding his uproarious story about a fellow guide breaking his tailbone on the limestone boulder (“In this exact spot!”) where we now stand.

The stocky, half-Mayan Luis is right: A slip here would indeed be bad. A ten-foot fall filled with jagged stalagmites sits on one side, while priceless Mayan ceremonial bowls wait on the other.

Arriving at this point — trying my damnedest not to break my ass or destroy invaluable artifacts — had been the caving adventure of a lifetime. Full disclosure: It also happened to be my first caving adventure.

Just about any idiot like me can safely navigate Belize’s guide-required Actun Tunichil Muknal cave. Located east of San Ignacio in the thickly jungled Cayo District, “ATM” is Belize’s premier caving experience.

There are bigger caves in Belize and there are caves you can leisurely float on inner tubes, but none of Belize’s publicly accessible caves match ATM’s adventurous and up-close look at Mayan ceremonial sites, filled with ceramic bowls and calcified human remains.

The Ancient Maya (approximately 2000 BC-1697 AD) believed caves were the entrance to the underworld, holy places where only shamans and their human sacrifices dare enter. As Mayan civilization reached its zenith and then began a prolonged decline, ceremonial activity in caves increased. Mayan ceremonial remnants exist throughout Belize’s extensive cave systems, but ATM seems to have held a special allure to the area’s Maya. Nowhere else in Belize have so many artifacts and intact human remains been found. Locked away undisturbed for hundreds of years, the cave’s contents remain eerily the same as when left by the Maya.

After donning closed-toe shoes, Black Diamond climbing helmets with waterproof Petzl halogen headlamps, our eight-person group quickly hikes the three-mile approach trail, crossing three knee-deep rivers en route to ATM’s mouth. The caving officially begins with an invigorating 50-foot swim, fully appreciated in the hot, muggy jungle.

After the swim, we wade through waist-deep water into a series of stalactite-laden mini-chambers leading to shoulder-width, neck-deep waterways. We quickly turn on our headlamps, illuminating the glittery crystalline cavern walls. I bounce on my tippy toes, using every inch of my 5’9” frame to stay above waterline.

Landing on a pebbly beach, we access our first significant chamber, housing a ceremonial site atop an eight-foot shelf. Luis shows us exactly where to place our hands and feet for the scramble up the small ledge. Atop the 12-foot-wide plateau, we huddle around a cluster of ceramic bowls, shattered remnants, save one thigh-high bowl lying on its side.

“My grandmother, full-blood Maya, would do ceremonies like this — build a fire and sacrifice bowls. See,” Luis shoots his laser pointer on a half-dollar-sized hole on the surviving, car-tire-sized ceramic bowl.

“These are kill holes inflicted by the Maya during their ritual, sacrificing these vessels to the gods. Remember, back then, vessels transported water, food, goods; they were life. This was a meaningful ceremony, a valuable sacrifice, meant to please the gods.” Luis is emphatic, a believer.

Descending the shelf proves much trickier than ascending. The safest route, as the cat-like Luis deftly demonstrates, is to face the wall and properly down-climb the small rock face, leading with feet.

Two group members eye the ledge nervously, but Luis quickly convinces them to turn around and trust the footholds, even physically placing their feet onto ledges and stalagmites at points.

Heading deeper into the cave, we begin wading through more waist-deep water, eventually plunging into winding, three-foot-wide passageways. We push along with our hands, the dank, pockmarked limestone walls providing surprisingly solid purchase.

With seven other headlamps on, I turn mine off and let my eyes adjust. I’m forced to feel my way through the cave, cautiously searching the cave walls with my hands and feet.

I recall Luis telling us earlier how the Maya navigated the cave using only the illumination from a pitch-pine torch. This is how to explore a cave, I think, feeling good about my headlamp decision. I love the cave’s quiet, its darkness, and the healing, comforting nothingness.

After grooving along in silence a while longer, the group convenes beneath a seven-foot ledge with a simple chimney scramble. Luis leads the easy scramble up. Atop the ledge, he instructs us to remove our shoes.

“We now enter the inner chamber,” he says.

I follow Luis, ascending one last, “easy-up” ledge before I am gobsmacked: The chamber ceiling is 75-feet tall, dripping with crystalline stalactites the size of small cars. Everything glitters like a chandelier. I’m entranced.

Then I look down.

Ceramic-strewn ceremonial sites fill the chamber floor, intact bowls, shards and piles everywhere. I look at my feet and realize I’m standing mere inches from an overturned bowl and human bones.

“Here we find our first human remains. Okay,” Luis closes his eyes and releases a deep breath. The group silently collects around the site, one massive bowl lies on its side, kill hole visible, while half-covered calcified bones sit nearby.

“Now the Maya are desperate, doing ceremonies to appease the gods — in reaction to environmental problems — drought, volcanos, crop failure. Maybe. Maybe warfare. Maybe all. We don’t know one hundred percent why. Times are bad so they make their greatest offer — a human life… We might be looking at the beginning of the Maya collapse.

“We think he is about 40 years old when sacrificed, old for that time. He lived a long life and probably felt honored giving his life to the gods. He was decapitated and placed in the fetal position.”

The group remains silent. Everyone stares at the bones, a clearly distinguishable femur, some spine and an unmistakable skull — all calcified from a millennia-long internment in this dripping tomb. Luis stands up and motions us forward.

We pass several more ceremonial sites with broken and overturned ceramics, scattered bones. Luis points them out as we press on toward a side chamber.

Coming to a hole about 10-feet deep and piled with splintered stalactites, Luis squats beside it and instructs us to turn off our headlamps as we gather around him. He shines his headlamp into the toothy pile.

“It’s hard to see but here we have another human skeleton. This is from a boy, about nine-years old. He was placed in the hole and covered with these rocks so that he slowly crushed to death with every breath. This is a more desperate plea to the gods; they want help.”

Stunned, we follow Luis onward to an opening along the chamber’s back wall. He doesn’t say anything, but we all silently know where he’s leading us. The last stop of the tour is also its most famous — a nearly complete, calcified skeleton known as the “Crystal Maiden.”

“The skeleton is misnamed,” Luis laughs, sitting at the skeleton’s feet. “We now believe the remains are from a man, not woman. Of course, he is also not crystal, but calcified,” his eyes dart upward, “like everywhere in the cave.”

Laying neatly on his back, the skeleton formerly known as Crystal Maiden is magnificent. The nearly intact spinal column and skull, arms, legs, collarbone, feet sparkle under the glow of our headlamps.

He’s beautiful and almost serene, but for his tortured look reminding us he’s a relic of a failing civilization’s last gambit. I wonder: Did he die scared? Proud? I can’t shake the feeling he probably felt as desperate as his once-thriving society, willing to try anything to save an imperiled future.

Our silent vigil complete, we quietly retreat, single file, from the main chamber, carefully avoiding the ceremonial artifacts that our adjusted eyes can now plainly see litter the chamber floor. We stick to the ridges that run like veins through the porous limestone.

At the head of the line, I stop at the “easy-up entrance” — our shoes now in sight. It’s far more menacing standing over it. I cautiously scan the stalagmite-filled left side and priceless-artifact-packed right side.

“So, just go, huh?” I sheepishly ask Luis.

“Sure, but be careful,” Luis laughs, before launching into his story about the guide who broke his ass. “In this exact spot,” he emphasizes.

I glance over my shoulder for one last look at the chamber ceiling, then uneventfully shuffle down the embankment to our shoes. The group follows and we begin our return trip through the cave, coccyxes and artifacts no worse for the wear.

It’s somewhere in the narrowing chambers, wading up to my waist, when I realize I’m in the absolute coolest place in Belize, if not all of Central America. On a 95-degree, searing jungle day, I’m wading through brisk freshwater in a cavern deep below ground, communing with long-gone Maya.

Practicalities

Getting here: About two hours of paved highway from Belize City, you can hire a car or driver at Philip Goldson Airport, coordinate a shuttle through your lodging or hop on one of the many colorful and dodgy-looking buses plying this popular stretch.

Book a tour: There are 27 certified guides, but there is only one Luis Zaiden. Book through your lodging by specifically asking for him (they’ll know) or via his website. Luis has been exploring and documenting area caves for over 30 years. He thoughtfully answers all questions, often proffering modern connections to ancient Mayan rituals. He also leads the local archaeology research group. Hiring a guide is mandatory. Guides provide helmets, headlamps and a hearty, post-cave lunch. No cameras allowed. Closed-toe shoes and socks required. www.kawiiltours.com

Stay: The San Ignacio area boasts countless hotels, guesthouses, resorts, jungle lodges and eco-lodges but none offer the value, intimacy and level of service as Amber Sunset Jungle Resort. Amber boasts a small jungle pool with poolside bar, six thoughtfully designed thatch-roofed “treehouses” and a locally sourced, rotating-menu, palapa-style restaurant. But what really sets it apart? Location. It catches ALL the breeze — not to mention the “amber sunsets.” A consummate hotelier, General Manager Giovanni Pelayo sited his six buildings underneath the existing jungle canopy to minimize tree removal. As a result, the birds stayed — you’ll see several different species just over breakfast — and the natural jungle canopy keeps his property several degrees cooler. Breeze, birds, views and shade — four priceless assets for a jungle lodge. www.ambersunsetbelize.com

Eat: Meats (including highly sought Gibnut), tropical fruits, vegetables (particularly peppers and root veggies), pressed-on-demand juices, prepared foods, woodcrafts, handmade clothes, hammocks and happy people, the San Ignacio Saturday Market is Belize’s best outdoor market. People come from across the country to buy and sell, meet and eat. Plan your jungle trip around a weekend and you should, too.