What a lot of people get wrong about Son Doong is just how massive it actually is. To put it into perspective, this cave could swallow dozens of New York City blocks—skyscrapers and all. It's so large that it even has its own weather system with mist and clouds floating inside.

In fact, the 2017 movie Kong: Skull Island used the surrounding Phong Nha-Ke Bang National Park as a filming location, capturing some of the mysterious and otherworldly landscapes that make the Son Doong area so unique. Now you know where they probably got the idea for the “inner earth”.

Where Exactly is Son Doong Cave?

The cave is nestled deep in Quang Binh Province, Vietnam, within the lush, protected boundaries of Phong Nha-Ke Bang National Park.

Son Doong Cave is a UNESCO World Heritage Site. It’s not just about size though (although it's definitely

The cave itself stretches over 9 kilometers (5.6 miles) and boasts ceilings that soar as high as 200 meters (660 feet). For context—the sheer height of this cave could comfortably fit The Big Ben, the Statue of Liberty, and your ex’s ego all in one go. This thing is a beast.

The World’s Wildest Cave Has an Even Wilder Backstory

Perhaps the biggest irony is that the world’s largest cave wasn’t found by a team of seasoned explorers and scientists with their high-tech equipment, but by pure chance in 1991, by a local man named Hồ Khanh, who stumbled across the entrance while searching for agarwood.

That’s it. Agarwood.

But spooked by the creepy sounds of rushing water and the wind blasting from the cave’s entrance, he left and soon forgot about it. Later, Hồ Khanh casually mentioned this “weird cave” to two British explorers, who somehow convinced him to find it again, which he did in 2008. By 2009, the world knew about Son Doong, and finally, the cave was opened for public tourism in 2013 — all because of a chance encounter in 1991.

When to Visit: Best Time and Weather

Son Doong only opens up for exploration from January to August. If you’re planning the trip of a lifetime, aim for March to May when the weather is chef’s kiss perfect. During these months, you’ll get temps inside the cave ranging between a cool 22-25°C.

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But here’s the kicker: the microclimates vary within the cave itself, making certain sections feel like different worlds altogether. In some chambers, it’s misty and humid with 90% humidity, thanks to natural skylights that let moisture seep in. Other parts, like the underground jungle, are warmer and bathed in filtered sunlight—almost like a hidden tropical zone.

Son Doong closes down from September to December because, well, it’s a giant cave, and water doesn’t exactly play nice during the rainy season. Even if you had the nerve to wade through, many sections of the cave would be completely inaccessible.

Packing Essentials for Son Doong

• Clothing: You want breathable, moisture-wicking layers that won’t stick to you like a bad breakup. Throw in a waterproof jacket (because the jungle trek to the cave entrance could get a bit soggy), and pack a cozy sweater for those chillier cave sections.

• Gear: Your cave trek will feel a lot more manageable with a headlamp to light up the dark, a pair of walking sticks to save your knees on uneven terrain, and a water bottle. The good news is that the tour operator will hook you up with the fancy climbing gear you need to conquer the trickier parts, so no need to bring that yourself.

Slather on that sunscreen before your jungle trek (the sun doesn’t care that you’re heading underground), and don’t forget insect repellent — if there’s one thing worse than a mosquito bite, it’s 10 of them when you’re miles from civilization.

How to Get To Son Doong

Getting to Son Doong is no walk in the park. (If it was, the world’s largest cave would’ve been discovered and opened way earlier than 2013.)

The journey consists of three parts. The first requires you to get to Dong Hoi, the nearest city. The second leg is from Dong Hoi to Phong Na, where you’ll join the tour group who’ll join you on your trek to Son Doong.

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So you can skip the frustration and focus on exploring all that Vietnam has to offer.

1. The First Leg of The Journey — Getting to Dong Hoi

Located about 45 kilometers from Phong Nha, Dong Hoi is your gateway to this epic caving expedition. It’s a small, sleepy coastal city, but it’s got enough to get you prepped before you disappear into the jungle.

By Plane: The Quick Route

Flying is hands-down the fastest way to get close to Son Doong. You’ll fly into Dong Hoi Airport from Hanoi or Ho Chi Minh City.

• Flight Duration: A breezy 1.5 hours.

• Cost: Ranges between 1,200,000 and 2,300,000 VND ($50-$100 USD), depending on how early you book.

By Train: The Scenic (but Slow) Way

If you prefer to channel your inner adventurer and soak in Vietnam's countryside, then hopping on the train is your move. The overnight trains from Hanoi or Da Nang take about 9-10 hours, which might sound long, but you’ll get to snooze and stare at some killer views along the way.

From Hanoi or Da Nang, the overnight trains to Dong Hoi take about 9-10 hours.

Ticket Prices:

• Hard Seat: 460,000 VND ($20 USD) – basic but gets the job done.

• Soft Seat/Sleeper: 1,380,000 VND ($60 USD) – more comfy, especially for long rides.

By Bus: The Sleeper Bus (aka the Backpacker’s Choice)

If you’re traveling from Hanoi or Hue, there are plenty of sleeper buses that’ll get you to Dong Hoi. The ride takes 8-12 hours, depending on traffic, but the cost is a sweet deal at 350,000 to 575,000 VND (around $15-$25 USD).

These buses are a solid budget-friendly option, and they usually roll in at weird hours, so make sure you’re mentally prepared to step off the bus into Dong Hoi when everyone else is still asleep. And yes, you will get to lay down—these are cozy sleeper buses.

2. From Dong Hoi to Phong Nha

Once you land in Dong Hoi, the real adventure kicks off as you head toward Phong Nha-Ke Bang National Park, which is where your Son Doong journey begins.

You’ve got a couple of options:

1. Taxi: It’s a 45-minute ride, and a private taxi will cost you about 700,000 VND (around $30 USD). It’s quick and painless, especially if you’re short on time or just need a chill ride to prep for the cave trek.

2. Local Bus: Feeling thrifty? Hop on a local bus for around 45,000 VND (about $2-3 USD). It’ll take you about 1.5 hours, but it’s the cheapest option and gives you a taste of local life before you disappear into the wilderness.

The third leg is part of an organized tour that we’ll cover in detail later down the blog.

Permits and Regulations — Your Golden Ticket to Son Doong

As lovely as it may sound, you can’t just roll up to Son Doong and start snapping selfies. You’re going to need a permit to enter—and they don’t hand them out like candy.

Permits are tightly controlled to protect the cave’s pristine condition, and only a limited number of expeditions are allowed each year.

You’ll need to book through Oxalis Adventure, the one and only operator that has the authorization to lead these expeditions. It’s not just a recommendation, it’s the law.

Health Check: Time to Prove You Can Handle It

Unfortunately, you can’t expect to show up with your gym membership card and breeze through this. You’ll have to pass a mandatory fitness test before the trip to make sure you're up to the challenge. This trek is no joke—it’s 4 to 6 days of hauling yourself through jungles, swimming in rivers, and scaling walls.

Don’t wait until the last minute to book. Trips to Son Doong sell out months in advance because only a few hundred lucky souls get to enter each year. If you’re serious about this adventure, get your name on that list ASAP!

And this should go without saying, but under no circumstances should you sneak in without authorization.

Son Doong Will Take Your Breath Away (and Your Wallet)

The Son Doong expedition costs a whopping 70,000,000 VND ($3,000 USD) per person. A price tag about as huge as the cave itself, but this fee covers all gear, guides, permits, food, and transportation within the park. Book only through Oxalis Adventure, as it holds exclusive rights to the cave. 

They offer different packages depending on the time of year and group size. Make sure you have a travel insurance for Vietnam that covers adventure activities, as it's often required for participation.

VII. Food, Accommodation, and Connectivity During the Expedition

1. Accommodation

This is as outdoorsy as it gets. The tour will set you up with campsites near the cave entrance and some inside the cave itself. Most camps have the basics covered—tents, sleeping bags, and shared facilities.

Toss a good thermal blanket or extra socks in your bag—you’ll thank yourself later when the temperature dips.

2. Food

Meals are provided and they’re perfect for the trek. Think local Vietnamese dishes that’ll fuel you up after a long day of hiking, climbing, and wading through underground rivers. You’ll get hearty portions of rice, veggies, and savory soups, with loads of vegetarian options. 

That said, you’re out in the wild, so don’t expect gourmet; instead, expect good fuel to keep you going.

3. Connectivity

Breaking it to you gently: no mobile signal or Wi-Fi. You’re officially off the grid inside Son Doong Cave and throughout Phong Nha-Ke Bang National Park. 

Honestly, that’s part of the magic. It’s just you, your fellow explorers, and the ancient, untamed beauty of nature. Give your loved ones a heads-up that you’re going radio silent for a few days.

The Son Doong Cave Expedition: A Day-by-Day Breakdown

Day 1: Arrival in Phong Nha – Briefing and Gear Check

After arriving in Dong Hoi City by 3:00 PM, you’ll be greeted by the friendly Oxalis staff at the train station or airport. They’ll whisk you away to your accommodation at Son Doong Bungalow in Phong Nha, where you’ll settle in and catch your breath.

Also, here's a heads up: the briefing is mandatory—missing it could mean you forfeit your spot on the expedition (no refunds, sorry!). So, pay attention, because this is where your adventure truly begins.

Gear Check

Dinner & Prepping for Tomorrow

After the briefing, you’ll head to Oxalis Home for a welcome dinner with the crew and fellow adventurers. This is your chance to break the ice with your new cave companions—you’ll be spending the next few days trekking through underground rivers and scaling walls together, so start bonding now!

Once dinner wraps up, it's back to your hotel to prep your gear and get a good night’s rest. You’ll need all the energy you can muster for the days ahead.

Timing

The briefing and gear check will take about 1-2 hours, followed by a leisurely dinner. Then, it’s time for some much-needed sleep to kick off the adventure fresh.

What to Watch Out For

• Gear Check:

• Weather: Phong Nha can get steamy, especially from April to August, with temperatures around 30°C (86°F). Stay hydrated and wear light clothing before you enter the much cooler cave system.

Day 2: Journey Through Doong Village to Hang En Cave – The Real Start of Your Adventure

Day 2 is when your Son Doong expedition truly kicks into gear, and it’s a full-on trek through jungles, rivers, and caves. Spoiler alert: It’s going to be sweaty, muddy, and absolutely epic.

What to Expect

Your day starts early. By 9:00 am, you'll be on the move after handing over your main bag (which Oxalis staff will transport to the campsite for you), so keep that handy 7 kg backpack for essentials only. After breakfast, you'll hop on the Oxalis bus for about 1 hour to the starting point.

Then, get ready for a steep 350-meter descent. We're talking serious downhill trekking into Phong Nha-Ke Bang National Park. After the descent, you’ll trek through the forest with stream crossings (yes, knee-deep water and soggy socks included) for about 30 minutes before arriving at Ban Doong, a small village inhabited by the Bru-Van Kieu ethnic group.

Meet the Locals & Fuel Up

You’ll stop at the house of the village elder for lunch, where you can learn about life in this remote area. It’s a peaceful break, but don’t get too cozy—there’s a lot more adventure ahead.

From Ban Doong to Hang En Cave

After lunch, it’s time to hit the trail again for about 3 hours. The path ahead includes more river crossings, slippery rocks, and stunning landscapes. This is where the jungle gets real. You’ll cross through rivers (and yes, you’re going to get wet, so embrace it) and navigate through thick foliage before entering Hang En Cave—one of Vietnam’s most jaw-dropping natural wonders.

Camping at Hang En Cave: The Grand Finale of Day 2

You’ll enter Hang En Cave through a small entrance, and after crossing the underground river and climbing a small hill, you’ll be greeted by your spectacular campsite, nestled beneath the high, wide cave entrance. This is where the magic happens.

Here, you'll find your pre-set tent (labelled with your name) and can kick back by swimming in the nearby lake after a long day of trekking. Not a bad way to wind down, right? As the sun sets, you’ll enjoy a delicious dinner prepared by the Oxalis team before resting up for the big day ahead: Son Doong itself.

Watch Out For:

• River crossings: Get ready to wade through streams—waterproof your essentials and be prepared to get wet.

• Steep descents: The 350-meter descent is not for the faint of heart—watch your step, especially in the slippery, forested sections.

• Leeches: Yep, they’re out there, lurking. They’re harmless but annoying, so keep an eye out.

Consider hiring a porter if you don’t want to lug your backpack through the jungle. For around $20-30/day, you can focus on trekking without the burden. Also, remember, if you’re struggling on this day, your guides may ask you to return to the base camp. Safety first, always.

Temperature & Weather

Expect warm, humid jungle conditions with temperatures reaching around 30°C (86°F). The humidity will be high, so stay hydrated and pace yourself.

By the end of Day 2, you’ll have trekked through the wilderness, crossed rivers, and camped in one of the most awe-inspiring caves on Earth. But remember, this is just the beginning—the real adventure starts tomorrow.

Day 3: Descending into Son Doong – Campsite at Doline 1

For adrenaline junkies, this is where the adventure gets real. On Day 3, you'll head to the entrance of Son Doong Cave after a scenic river trek from Hang En Cave (yes, where Peter Pan: Pan and Neverland was filmed—bonus bragging rights!). The final steep climb brings you to the dense forest at Son Doong Cave entrance.

What to Expect

Once you arrive, you’ll get suited up with safety harnesses, karabiners, and other equipment as part of a detailed safety briefing from your guide. As you approach the entrance, you’ll feel a rush of cold air thanks to the difference in temperature and pressure between the inside and outside of the cave—nature’s air-conditioning. The descent into the cave begins, and this isn't some casual walk down. This is a full-scale descent using ropes, guided by a team of safety experts who will ensure you're equipped to rappel down like a pro.

Once at the bottom, the real journey begins. You'll cross two rivers, navigate rocky slopes, and encounter enormous stalagmite formations, including the legendary Hand of Dog—a towering, paw-like structure.

• Time to Spend: The entire descent and exploration of the first chambers take 4-6 hours. This time includes the slow and steady descent, the river crossings, and a hike through some jaw-dropping chambers. Remember, this isn’t about speed—every corner you turn will blow your mind, so take it all in.

• Microclimates: The inside of the cave has its own microclimate, which you’ll feel right away. Temperatures inside range from 17°C to 22°C (62-72°F). It's cool, damp, and constantly misty, creating an atmosphere that feels like a sci-fi movie set. As you descend, you’ll feel the humidity, so be prepared for that clammy feeling.

• Flora/Fauna: Keep an eye out for moss, fungi, and even small cave-dwelling creatures like bats. The low-light environment is alive with strange, adapted organisms that thrive in this underground ecosystem.

Don’t forget your GoPro or low-light camera. The vast chambers and towering rock formations are a photographer’s dream, but you'll need gear that can handle the cave's dim lighting.

After reaching the first campsite, known as the Level Playing Fields just before Doline 1, you’ll have the option of swimming in a cold underground pool—the perfect way to refresh after the trek. The water here ranges from 17°C to 22°C, so bring a life jacket, and get ready to cool off in a seriously surreal environment.

And of course, a hearty dinner awaits you to round off your day. After all, you’ve just taken on one of the world’s greatest caves.

Day 4: The Garden of Edam and Doline 2

What to Expect

Your first stop is the Watch Out for Dinosaurs section, a part of Son Doong known for its prehistoric appearance and awe-inspiring landscape, which makes you feel like you've stepped back into a time when dinosaurs roamed the Earth. This section features massive stalagmites, dramatic rock formations, and the misty atmosphere of the cave, all contributing to its eerie, otherworldly feel.

While there aren't any actual dinosaurs (thankfully), the towering formations and the cave's unique atmosphere create an illusion of a prehistoric past.

After this, you’ll descend deeper into Son Doong, where you'll stumble upon the Green Gours, a beautiful spot known for its emerald calcite formations. This area lights up thanks to the emerald, especially on sunny days, when sunlight streams in, illuminating the calcite pools with vibrant green hues.

Following this, you’ll make your way to the Garden of Edam, a surreal ecosystem located at Doline 2. It’s as if Mother Nature decided to plant a secret garden right inside the belly of the Earth. Trees, ferns, and other vegetation thrive in this pocket of life, all thanks to the sunlight pouring through the collapsed cave ceiling above.

• Time to Spend: This part of the journey can take 4-6 hours, including lunch breaks and plenty of time to absorb the views, navigate the tricky paths, and, of course, capture the incredible scenery. You'll end the day at your campsite near Doline 2.

• Microclimates: The temperature in this section remains relatively cool, between 22-25°C (72-77°F), but the humidity will make it feel much damper. Be prepared for mist and possible cloud formations due to the mix of air from the outside environment and the cave's natural moisture. It's like stepping into a jungle wonderland hidden deep underground, with its own weather system. You may even see clouds hanging low within the cave—a truly magical sight.

• Flora and Fauna: The Garden of Edam boasts an abundance of plant life, including tree ferns and vines. You might spot some cave-dwelling critters like bats and cave crickets, and though the fauna isn't extensive, it's impressive to see life thriving in such an isolated ecosystem.

This is your last night camping inside Son Doong, so make it count! After setting up camp, take some time to relax and soak in the breathtaking views of the Garden of Edam. And don’t forget—you’re deep inside a cave with no bathing facilities, so wet wipes and dry shampoo will go a long way in terms of hygiene.

Campsite Vibe

Once you’ve set up camp at Doline 2, you’ll be treated to yet another hearty dinner. This is the perfect time to unwind, review your photos, and bond with your fellow adventurers under the shelter of the cave. Keep in mind that there are no showers at this site, so be prepared for a bit of a “roughing it” vibe, but trust me, the view more than makes up for it.

Day 5: Conquering the Great Wall of Vietnam and Exploring the Final Chambers

What to Do

Start your day with a hot cup of coffee and prepare for an adrenaline-pumping challenge: The Great Wall of Vietnam. This section is all about pushing boundaries. After breakfast, you'll be equipped with safety gear and given a short safety briefing before tackling this 60-meter giant. Depending on the weather, your experience will vary. On rainy days, you’ll be treated to a lake at the base of the Wall and the chance to row a raft across it. On other days, expect a muddy trek through Passchendaele Passage, a slippery, muddy section that will test your endurance.

Once at the base of the Wall, you’ll ascend an 18-meter stainless steel ladder and then continue climbing the ropes up a 72-meter slope at a steep 45-degree angle. It’s a thrilling mix of rope work and climbing that’ll make you feel like a true adventurer.

• Time to Spend: 4-6 hours. You’ll need plenty of time to navigate this challenging ascent, and the safety team will guide you every step of the way. It’s not just a climb; it's a once-in-a-lifetime experience.

• What to Watch Out For: The climb is steep and requires a good level of physical fitness. But fear not—there will be safety assistants stationed at various points to ensure you’re securely harnessed and safe throughout the entire climb. Even if you’re feeling nervous, their support and guidance will give you the confidence to push through.

• Microclimates: As you ascend, you’ll experience cooler, drier air around 20°C (68°F). The temperature here can vary slightly depending on the season and weather outside, but the feeling of crisp air and mist swirling around gives you a sense of the cave’s incredible ecosystem.

• Flora & Fauna: Keep an eye out for unique cave creatures like blind spiders, woodlice, and fish that have adapted to the darkness of this cave for millions of years. You might even come across cave pearls, rare natural formations that have developed over centuries due to dripping water.

Once you’ve conquered the Wall, take a moment to pause and soak in the incredible view from the top. It’s the perfect photo op and a well-deserved break. Afterward, you’ll enjoy lunch at the summit before beginning the final trek out of the cave.

Day 6: Wrapping Up Your Adventure – Chay Lap Farmstay and Beyond

After days of intense exploration, Day 6 is your chance to wind down, reflect, or squeeze in a little more adventure before heading out. Your stay at Chay Lap Farmstay provides a serene backdrop to recover from your Son Doong expedition and offers plenty of opportunities for one last taste of Phong Nha’s natural beauty.

What to Do

Depending on your energy levels, you can choose a relaxed morning at the Chay Lap Farmstay, surrounded by lush greenery, or dive into one last adventure. Phong Nha has no shortage of activities to enjoy before you leave. Paradise Cave or Mooc Spring are beautiful nearby spots, or, if you’re still craving action, head over to Chay Lap Water Sport Center for kayaking or paddleboarding.

For the more daring, renting a motorbike or bicycle is an excellent way to explore the surrounding Phong Nha-Ke Bang National Park or the Bong Lai Valley. Just a friendly reminder: Vietnam’s roads can be chaotic, so make sure you’re confident in your driving skills before hitting the road.

• Time to Spend: Allow 3-4 hours in the morning if you want to explore nearby attractions, but make sure to leave enough time for your travel preparations.

• What to Watch Out For: Double-check check-out time, which is before 12:00 PM, so plan your activities accordingly. If you need to extend your stay, inform the Oxalis sales team ahead of time.

• Packing Tip: If you're heading straight to the airport or train station after breakfast, have your bags packed the night before, so you're not rushing through your last moments in Phong Nha.

• Departure: Oxalis can arrange a pickup to take you to the Dong Hoi airport or train station, depending on your exit strategy. If you’ve got a little extra time before your departure, ask the staff for recommendations on one last spot to visit—they’ll know where to direct you for a perfect final memory.

If you're still craving adventure, Oxalis runs tours to other incredible cave systems like Hang Va, Hang Tien, or even Tu Lan (where Kong: Skull Island was filmed). These expeditions are entirely different from Son Doong and can extend your experience from 1 to 6 days. Perfect if you’re not quite ready to head back to reality yet!

Son Doong is a Dance With Nature's Raw and Untamed Beauty

Each day spent trekking through mist-filled chambers and lush underground jungles deepened your connection to something greater—something primal, untouched, and extraordinary.

But here's the thing: Son Doong is just a sneak peek into what Vietnam has to offer. If your adventurous spirit is still hungry for more, the journey doesn’t have to end here. Oxalis is ready to lead you into other jaw-dropping cave systems like Hang Va or Hang Tien, or even take you to Tu Lan, where you can channel your inner King Kong. These expeditions vary in length—anywhere from a single day to a full six—and will take you on entirely different paths of exploration.

So whether you’re ready to dive back into the bustle of daily life or feel like staying off-grid just a little longer, know that Vietnam will always have a corner waiting for you to uncover.

The journey might be over for now, but there’s always another horizon—another thrill—just waiting around the bend.

In our previous blogs in this series, we covered our review of Vietnam Airlines, an arrival guide to Hanoi’s Noi Bai International Airport, transport options in Vietnam, a guide to Hanoi, and a beginner's guide to exploring Vietnam.