Spelunking: 12 Spectacular Caves Worth Exploring

Beneath the surface of the Earth lies an entirely different world. A world of cathedral-sized chambers dripping with stalactites, underground rivers that have never seen sunlight, and passages so narrow you have to exhale to squeeze through. Caving, also known as spelunking or potholing, is the adventure sport that takes you into these hidden spaces, and the experience is unlike anything else in the outdoor world.

In 2026, adventure caving is more accessible than ever. From guided tours in well-developed show caves to multi-day expeditions into some of the planet’s deepest and most remote underground systems, there is a caving experience for every level of fitness, courage, and claustrophobia tolerance. This guide covers the most spectacular caves on Earth, from beginner-friendly tours to expert-level expeditions that will test every ounce of your resolve.

Hang Son Doong, Vietnam: The World’s Largest Cave

Hang Son Doong is not just a cave. It is an underground world. Discovered in 2009, this cave in Phong Nha-Ke Bang National Park is the largest known cave passage on Earth, with sections large enough to house a 40-story skyscraper. Inside, you will find its own jungle ecosystem complete with its own weather system, clouds forming near the ceiling where skylights allow sunlight to penetrate.

Visiting Son Doong is a genuine expedition. The only way to enter is through Oxalis Adventure Tours, which holds the exclusive permit. The trip takes four days and three nights, with camping inside the cave, river crossings, and a challenging jungle approach.

Difficulty: Moderate-Hard (requires good fitness, basic climbing ability) Duration: 4 days / 3 nights Cost: Approximately $3,000 per person (all-inclusive, including porter support, meals, camping gear) Season: February through August (dry season). Limited to about 1,000 visitors per year. Getting there: Fly to Dong Hoi, then transfer to Phong Nha (45 minutes). Where to stay (before/after): Phong Nha has hostels from $8 per night and hotels from $25.

Pro Tip: If Son Doong is out of your budget, Oxalis also operates tours of Hang En (the third-largest cave in the world) for about $350 per person for a 2-day trip. The experience is still extraordinary.

Photo credit on Pexels

Mammoth Cave, Kentucky, USA: The World’s Longest

With over 400 miles of surveyed passages (and more being discovered regularly), Mammoth Cave is the longest cave system in the world, more than twice the length of any other known cave. The cave has been a National Park since 1941, and the National Park Service offers a range of guided tours from easy walks to strenuous crawling expeditions.

Tour Options

• Domes and Dripstones Tour (2 hours): The best introductory experience, featuring massive dome formations and delicate dripstone features. Moderate difficulty with some stairs. $18 per adult.
• Historic Tour (2 hours): Follows the original tourist route from the 1800s through massive chambers. Easy-moderate. $18 per adult.
• Wild Cave Tour (6 hours): The real deal. You crawl, climb, and squeeze through undeveloped passages far from the tourist routes. You will get muddy, tired, and exhilarated. $60 per adult. Reservations required months in advance.

Difficulty: Easy (tourist tours) to Hard (Wild Cave Tour) Season: Year-round (cave temperature is a constant 54 degrees Fahrenheit) Getting there: 90 minutes south of Louisville, Kentucky Where to stay: The Lodge at Mammoth Cave inside the park from $80 per night. Camping from $20. Cave City (nearby) has budget motels from $50.

Waitomo Glowworm Caves, New Zealand: Bioluminescent Magic

The Waitomo caves contain one of nature’s most extraordinary spectacles: millions of tiny glowworms (Arachnocampa luminosa, a species unique to New Zealand) that cover the cave ceilings with bioluminescent light, creating the effect of a starry sky underground. Multiple tour operators offer different levels of experience:

• Glowworm Grotto boat tour (45 minutes): A gentle boat ride through the glowworm-lit caves. Easy, suitable for all ages. From $50 NZD.
• Black Water Rafting (3-5 hours): You float through the caves on inflated inner tubes, jumping off underground waterfalls and drifting beneath the glowworms. Moderate difficulty. From $150-220 NZD.
• Black Abyss (5 hours): The full adventure package including abseiling into the cave, zip-lining, rock climbing, and tubing. Advanced. From $260 NZD.

Difficulty: Easy to Advanced (depending on tour) Season: Year-round Getting there: 2.5 hours south of Auckland by car Where to stay: Waitomo has budget accommodations from $25 NZD per night. Hamilton (1 hour away) has more options.

Actun Tunichil Muknal (ATM), Belize: Archaeological Underworld

ATM cave in Belize is one of the most remarkable archaeological sites in the Americas. The cave was used by the ancient Maya for ceremonies, and the artifacts, including pottery, stoneware, and human remains (including the famous “Crystal Maiden” skeleton), remain exactly where they were left over a thousand years ago. The journey to reach the ceremonial chambers involves wading and swimming through chest-deep water, scrambling over boulders, and navigating through tight passages. Photography is no longer allowed inside to protect the artifacts, but the experience is seared into your memory regardless.

Difficulty: Moderate (swimming required, some climbing) Duration: Full day (8-10 hours including transportation) Cost: $100-150 per person (guided tour required, includes lunch and transportation) Season: Year-round, but water levels are highest September-January Getting there: Tours depart from San Ignacio (2.5 hours from Belize City) Where to stay: San Ignacio has hostels from $12 per night and hotels from $40.

Photo credit on Pexels

Sarawak Chamber, Gunung Mulu National Park, Malaysian Borneo

The Sarawak Chamber is the largest known cave chamber in the world by surface area: 600 meters long, 435 meters wide, and 115 meters high. You could fit several football pitches inside with room to spare. The chamber is located within the Mulu cave system, which also includes Deer Cave (home to the world’s largest cave passage by volume) and the spectacular Clearwater Cave.

Tour Options in Mulu

• Deer Cave and Lang Cave (show cave tour, 3 hours): Easy walking through enormous passages. The evening bat exodus, when millions of bats spiral out of the cave at dusk, is one of nature’s great spectacles. From 30 MYR.
• Wind Cave and Clearwater Cave (3 hours): Underground rivers and stunning formations. From 30 MYR.
• Adventure Caving (Sarawak Chamber, 8-10 hours): Requires booking well in advance and a high level of fitness. The approach involves 2-3 hours of scrambling through mud and water. From 400 MYR per person.

Difficulty: Easy (show caves) to Hard (Sarawak Chamber expedition) Season: Year-round (tropical climate) Getting there: Fly from Miri or Kota Kinabalu to Mulu Airport Where to stay: Park accommodation from 40-120 MYR per night. Limited options; book in advance.

Holloch Caverns, Switzerland: Europe’s Longest

The Holloch cave system in central Switzerland extends over 200 kilometers, making it the longest cave in Europe and one of the longest in the world. Adventure caving tours range from beginner-friendly 3-hour excursions to multi-day underground expeditions.

Tour options:

• Beginner tour (3-4 hours): Introduction to caving with some crawling and climbing. From 90 CHF.
• Explorer tour (7-8 hours): Deeper penetration with more technical sections. From 150 CHF.
• Overnight expedition (12-24 hours): Camping underground, exploring remote passages. From 250 CHF.

Difficulty: Easy to Expert (depending on tour) Season: Year-round Getting there: Muotathal, 90 minutes from Zurich Where to stay: Muotathal has guesthouses from 50 CHF per night.

Marble Cathedral, Chilean Patagonia

While not a traditional cave, the Marble Cathedral (Catedrales de Marmol) on General Carrera Lake is one of the most visually stunning underground formations on Earth. Turquoise glacial water has sculpted marble rock into cathedral-like chambers over thousands of years. The swirling blue and white patterns of the marble, reflected in the water below, create an otherworldly visual experience. Difficulty: Easy (boat tour) Duration: 1-2 hours Cost: From $30-50 per person for a boat tour Season: November through March (Patagonian summer, calmest lake conditions) Getting there: Chile Chico or Puerto Rio Tranquilo on the Carretera Austral Where to stay: Puerto Rio Tranquilo has hostels from $15 per night and cabanas from $40.

Cueva de los Cristales, Mexico: The Crystal Cave

Located 300 meters below the surface in the Naica mine in Chihuahua, this cave contains the largest natural crystals ever found: selenite beams up to 12 meters long and weighing 55 tons. The cave is extremely hot (up to 58 degrees Celsius with 99% humidity) and without specialized equipment, a person can only survive about 10 minutes inside. The cave is not currently open to public visits (it was flooded when mining pumps were shut off), but it remains one of the most extraordinary geological discoveries in history. Researchers continue to study the cave, and there is hope that limited access may be restored in the future.

Essential Gear for Caving

Basic Gear (for guided tours and beginner trips)

• Helmet with headlamp: The most essential piece of caving gear. Never enter a cave without it. Budget: $40-80 for a helmet, $20-60 for a headlamp.
• Backup light source: Carry at least one additional light. Small LED flashlights or a second headlamp.
• Sturdy footwear: Boots with ankle support and non-slip soles. Purpose-built caving boots or sturdy hiking boots.
• Clothing: Synthetic or wool layers that will get dirty. Avoid cotton (it stays wet and cold). A coverall or old clothes you do not mind destroying.
• Gloves: Mechanics gloves or similar for hand protection.
• Knee pads: Essential for any cave with crawling sections.

Advanced Gear (for technical caving)

• Vertical caving kit (harness, rappel device, ascenders)
• Static rope
• Wetsuits (for caves with water)
• Dry bags for electronics and dry clothes
• Survey and navigation tools

Safety Rules

1. Never cave alone. The minimum group size is three: if one person is injured, one stays while the other goes for help.
2. Tell someone your plans. Leave your expected return time and cave name with someone reliable.
3. Carry three independent light sources. If all your lights fail underground, you are in serious trouble.
4. Do not touch formations. Stalactites, stalagmites, and other formations take thousands of years to grow and can be destroyed by a single touch.
5. Watch for rising water. Caves can flood rapidly during rain events.
6. Check for hazards. Bad air (low oxygen or high CO2), unstable rock, and wildlife (bats, snakes) are all potential concerns.

Photo credit on Pexels

Caving Destinations: Budget Comparison

Destination	Tour Cost	Daily Budget	Trip Duration
Son Doong, Vietnam	$3,000 (all-inclusive)	$20-40	4-5 days
Mammoth Cave, USA	$18-60	$50-100	1-2 days
Waitomo, New Zealand	$50-260 NZD	$60-100 NZD	1 day
ATM, Belize	$100-150	$25-50	1 day
Mulu, Malaysia	$10-130 MYR	$80-150 MYR	2-3 days
Holloch, Switzerland	$90-250 CHF	$60-100 CHF	1-2 days

Getting Started: Building Your Caving Skills

Your First Cave Trip

The best way to start caving is with a guided tour at a developed cave system. National parks and commercial caves offer structured experiences where you can gauge your comfort with darkness, tight spaces, and underground terrain without any technical skills.

Joining a Caving Club

The global caving community is organized through local “grottos” (caving clubs). In the US, the National Speleological Society (NSS) has over 250 local grottos that organize regular trips, provide mentorship for beginners, and maintain relationships with landowners who grant access to caves on private property. Benefits of joining a grotto:

• Access to experienced mentors who teach safe caving practices
• Group trips to caves you could not access independently
• Gear sharing and advice on equipment purchases
• Training in vertical caving (rope work, rappelling, ascending)
• Connection to the broader caving community and its culture of exploration and conservation

Annual NSS membership costs about $40, and most local grottos charge $10-20 per year.

Progressing Your Skills

The caving skill progression looks like this:

1. Horizontal caves (no ropes): Walking, crawling, and scrambling through passages. Focus on navigation, light management, and comfort underground.
2. Moderate caves with short climbs: Basic scrambling and chimneying (using opposing walls for support). Learning to read cave formations and geology.
3. Vertical caves (rope skills): Rappelling and ascending using specialized caving techniques (different from climbing rope work). Single Rope Technique (SRT) courses are available through many grottos and outdoor centers.
4. Expedition caving: Multi-day underground trips with camping, surveying, and exploration of new passages.

Photography Underground

Cave photography is a specialized skill that produces extraordinary images. Key tips:

• Multiple flash units are essential for illuminating large chambers. A single camera flash produces flat, unflattering light.
• Long exposures with light painting (moving a flashlight across the scene during a long exposure) can create dramatic, evenly lit images.
• Protect your gear. Caves are wet, muddy, and abrasive. Use waterproof camera bags and handle equipment with clean, dry hands.
• Patience is everything. A great cave photograph can take 30 minutes or more to set up and execute.

Cave Conservation

Caves are fragile environments that take thousands to millions of years to form. Responsible caving means:

• Never touching formations (oils from your skin can halt growth permanently)
• Never removing anything from a cave (take nothing but photographs, leave nothing but footprints)
• Staying on established paths to avoid crushing delicate cave life
• Following decontamination protocols to prevent the spread of White-Nose Syndrome (a devastating bat disease)
• Reporting new discoveries to the caving community rather than publicizing them on social media (which can lead to damage from unprepared visitors)

Why Go Underground?

Caving offers something that no other adventure sport can: genuine exploration of terrain that most of humanity has never seen. When you crawl through a passage into an unexplored chamber, you might literally be the first human being to ever see it. That combination of physical challenge, discovery, and the visceral thrill of navigating the darkness makes caving one of the most rewarding adventure activities on the planet.

The caves on this list represent the finest underground experiences available, from the bioluminescent magic of Waitomo to the staggering scale of Son Doong. Start with a guided tour at a developed cave, build your skills and confidence, and then start exploring the deeper, wilder systems. Pair your caving adventures with off-grid wilderness camping for the ultimate underground expedition. The underworld is waiting, and it is more beautiful than you could possibly imagine. For world-class caving on a budget, explore the caves of Southeast Asia.

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