What You Should Know Before Planning A Spelunking Expedition

Taking a trip down under doesn't always mean heading to Australia. Caving — or spelunking as it's called — is a way to see the world in a whole new light, even if that light is from your battery-powered headlamp. As with any outdoorsy endeavor, there's a spectrum of adrenaline-inducing levels options, so knowing a few basics will ensure a good fit for your interest level. Do you want to explore this secret world walking upright in your athleisure wear or in specialized gear — on your belly — squeezing through impossibly small holes in the earth's core?

Most experts agree there are thousands of caves across the planet. Some are spacious walk-ins, while others require would-be adventurers to rappel down using a rope system. But generally, caves fall into seven categories, which World Atlas describes as sea caves, rock shelters, glacier, lava, eolian (formed by strong winds, eroding a rock wall over time), and talus — when boulders tumble into a pile, creating cavernous spaces. Talus caves, like those at Pinnacles National Park in California, are often considered young compared to the most common type — solutions caves — which National Geographic reports usually morph by way of groundwater wear over 100,000 years before a human can even shimmy into it.

If you're into art, caves offer the best sculpture collections

Caving is a Willy Wonka world of fascinations — speleothem mineral sculptures take every shape imaginable, from deep ceiling forests of craggy spires to sheet-like flowstones that cascade into mounds of otherworldly texture. One of National Geographic's cave-science tutorials explains that speleothem — the result of the interplay between the groundwater and the rock's minerals, creates these unique mineral formations. Along roofs of caves, you may see speleothem in the form of stalactites; the ones that form on the ground are stalagmites.

Water's presence in caves can also extend beyond the groundwater that may have contributed to the cave's origin story and crusty mineral formations, but some caves house entire underground lakes, which Fodor's suggests might be a nice break from our typical idea of lake life. Plus, you just might get an extraordinary glimpse of how life and cultures have evolved. Finally, because it's not just the unusual nooks, crannies, and mineral formations that are worth the effort, some caves are archeological sites that house ancient artifacts, cave drawings, and insight into human evolution.

Sir David Attenborough agrees -- cave creatures are wonderfully weird

The life of caves, however, isn't reserved solely for archeological digs. More than just the bats we hear so much about, caves are teeming with life. As one example, Geology reports over 7,700 species of animals (troglobites) have adapted to subterranean dwellings — and those are just the known species. Most experts agree that's just a glimpse of the total number; the vast majority have yet to be discovered.

The cool thing is, the folks at the National Caves Society note that you'll recognize most of them as everyday salamanders, beetles, fish, spiders, and snails. But, over time, these little creatures have adapted to cave life. So, if you imagine living in a cave for thousands of years, it's no surprise you'd become quite pale over time, like an elegant Goth tourist that went on a caving holiday and decided to stay. Plus, many are, in fact, blind since their evolutionary journey prioritized their other senses for survival's sake; and sight — in the darkest depths of caves — is less important.

The isolated nature of caves is like an artist's canvas where the most curious creatures take shape. So much so, troglobites are covered in the Netflix docuseries "Planet Earth," narrated by famed natural historian and broadcaster Sir David Attenborough. "This isolation," he says in the opening of a show clip featured on YouTube, "has resulted in the evolution of some very strange creatures."

The first rule of Cave Club is ... BYO light

Sure, there are plenty of caving adventures with manmade boardwalk systems, and many take place in caves where lighting has been installed. But if you're feeling plucky and want to dabble in deeper cave exploration, you should opt for a caving expedition company. Although GloboTreks mentions that spelunking involves skills you may already have — hiking, crawling, and potentially swimming — doing these things in a damp, dark maze of tunnels requires a professional guide. It's easy to get confused and get lost, so stick with the pros on this one.

One thing you'll need is light — and plenty of it. For optimum safety, your spelunk-sesh should include four to six other people, each carrying three light sources. And whether you're exploring with experienced friends or professionals, always let others know where you plan to explore. Why? Well, the film "127 Hours" sums it up.

It's the story of hiker Aron Ralston, who goes on a solo hike and squeezes through a rock formation. A boulder comes loose and crushes his arm. He was trapped for five days before making the unfathomable decision to amputate his own arm. Ralston is a highly experienced mountaineer and extreme sports athlete, but accidents happen. So tell friends and family, in advance, what cave you'll be exploring.

You'll also need some essential gear. So, plan on wearing a hard hat, comfortable clothes, and sturdy shoes. And in terms of what else to bring, The Travel Channel suggests that a first-aid kit, nutrient-dense snacks, and water should all be in your backpack. But remember, the deeper you go, the less oxygen there may be. So, bring some waterproof matches; if they don't light (due to lack of oxygen), avoid that space.

Claustrophobic? These roomier caves might be a good fit

Obviously, if you have the fear of small spaces associated with claustrophobia, you might take a hard pass on spelunking. But if you're curious, there are certainly some larger caves that — depending on your spatial needs — could still be comfortable — and fun. Take, for example, Mammoth Cave in Kentucky. It's managed by the National Parks System and is a UNESCO World Heritage Site and International Biosphere Reserve. Oh, and it's the largest known cave system in the world, with a tunnel system spanning over 400 miles. And within all those tunnels, there are multiple opportunities to focus on its larger spaces, often where rangers give talks.

Christy Woodrow, a claustrophobic traveler, stretched her comfort zone in the caves and caverns of Rio Secreto, a top-five activity in Playa del Carmen, Mexico, according to Tripadvisor. She said that asking a lot of questions in advance helped her prepare, and having a guide's expertise was very comforting.

And if these are still too tight for you, there are sizeable walk-in-style caves, such as Vietnam's Son Doong, the cave with its own rainforest inside. Its known for its ginormous caverns, as seen in this dynamic National Geographic web tour. And if you decide that a 360-degree tour is as close as you want to get to spelunking, at least these modern-day virtual tours give you a peek!

Cave salamanders have some competition -- cue the glowworms!

In the end, there are caves for every interest level — from a quick tourist outing to an all-out off-grid expedition. For those with mobility considerations or people who want to bring strollers (which is often not possible in a cave), Virginia's Luray Caverns is an excellent option since they have paved walkways. But if lake life is more your style, you can head over to Lost Sea Caverns in Sweetwater, Tennessee. Located within the larger Craighead Caverns system, it boasts the title of the largest (non-subglacial) underground lake in the United States, and Travel and Leisure suggests the glass-bottom boat tours are absolutely worth it. If you feel like drinking in a Croatian wine cave, it's just a flight away. Or, if you're looking to stay stateside, you can visit the 150-year-old beer cave in Iowa.

If casual subterranean meandering and chill underground boat tours don't quite do it for you, how about a New Zealand cave bustling with the ephemeral whimsy of glowworms? The Waitomo Glowworm Caves are filled with thousands of Arachnocampa Luminosa glowworms and are accessible by boat tours. The beautiful, glowy show — first discovered over 130 years ago — is part of a cave system that's 30 million years old and is a rare exception to the BYO light rule!