Son Doong Cave – the largest cave in the world – is a dream destination for thousands of adventure seekers. With its unique ecosystem, massive stalagmites, and two magnificent dolines (sinkholes), it has attracted 7,552 visitors from countries such as the US, UK, Australia, Canada, Vietnam, and more.
Each year, the Son Doong expedition tour is limited to only 1,000 participants, with strict requirements on physical fitness and trekking experience. Despite that, tours are often fully booked 8 to 12 months in advance. As of now, the 2027 tour season is sold out, and Oxalis Adventure has started opening slots for 2028.
To make sure you don’t miss the chance to explore this underground wonder, the guide below walks you through every step of booking a Son Doong expedition tour accurately and successfully.
What You Need to Know Before Booking the Son Doong Expedition
Here are the essential things you must consider before booking the tour to ensure a safe, fulfilling experience that complies with all regulations set by the tour operator:
1. Independent Access to Son Doong Is Not Allowed
Son Doong Cave lies deep in the core zone of Phong Nha – Ke Bang National Park, about 25 km from the nearest road. The terrain is rugged, involving forests, rivers, and complex cave systems. This area is strictly protected and not open to independent travel.
For safety and conservation reasons, all Son Doong expeditions must be arranged through Oxalis Adventure, the only company licensed to operate tours in this area.
If you see any other organization advertising or selling Son Doong tours, it is a scam. Be cautious and only book through Oxalis’s official channels to protect yourself.
2. Each Tour Has a Maximum of 10 Guests
Every expedition group includes up to 10 guests, supported by a team of 27 staff members: guides, safety experts, doctors, chefs, and porters. This extremely high staff-to-guest ratio ensures maximum safety and a personalized experience.
3. Assess Your Physical Fitness Honestly
The Son Doong trek spans 25–30 km over 4 days through challenging terrain: steep slopes, muddy paths, deep streams, and slippery rocks. It’s not for beginners or those with poor health.
You must submit an honest health declaration online when booking. Vague answers like “I go to the gym” are not acceptable. Instead, you must detail your actual exercise habits, intensity, and weekly frequency. Oxalis’s safety experts will use this information to assess your eligibility.
Individuals with heart, respiratory issues, high blood pressure, or general weakness are strongly advised not to register.
4. Strict Safety and Environmental Protection Rules
Son Doong is a pristine ecosystem. Touching stalactites, collecting samples, littering, or making noise is strictly prohibited. All waste is carried out by porters. Smoking is only allowed in designated areas, and no trace must be left behind.
For safety, you must stay with your group, follow the guide’s instructions, and never consume alcohol or drugs. In some sections of the cave, you’ll need to climb or cross rivers, so helmets, protective clothing, and safety harnesses are mandatory.
Step-by-Step Guide to Booking a Son Doong Tour
To embark on this once-in-a-lifetime expedition, you must follow a strict registration process and prepare well. Here’s how to secure your slot and get ready for your dream journey:
Step 1: Research the Tour
Visit Oxalis Adventure’s official website, the only licensed tour operator for Son Doong.
You will:
- Learn the fitness requirements and age limits (18–70).
- Review the 6-day, 5-night itinerary.
- Understand environmental conservation commitments and safety regulations.
- Check the tour price, currently around USD 3000 per person (all-inclusive).
- Note that only 1,000 slots are available per year and must be booked 6–12 months in advance.
Step 2: Choose the Best Time to Visit
Son Doong tours run from January to August, during Quang Binh’s dry season.
- January – March: Sunlight enters the dolines, creating magical photography opportunities.
- April – May: Lush greenery and blooming forests with mild weather.
- June – August: Warmer temperatures, ideal for swimming and adventurous activities.
- September – December: Tours are closed due to flooding. This is the cave’s recovery period.
Step 3: Submit Your Online Booking
Once you’ve selected your date, complete the online booking form via Oxalis:
- Choose your desired departure date.
- Provide personal info, health condition, trekking experience, and any medical history.
- You’ll receive a temporary booking confirmation by email (booking code).
- Oxalis will review your profile in 3–5 days and may contact you for more details.
Step 4: Confirmation and Payment
Once your profile is approved, you’ll receive an official confirmation and payment instructions. Accepted methods include international credit cards or bank transfers.
Once paid, your slot is confirmed. Note: bookings are non-transferable and non-refundable.
Step 5: Pre-Tour Support
After confirmation, Oxalis will:
Send a physical training guide tailored to the trek.
Provide a packing list and safety/survival tips.
Help you arrange accommodation in Phong Nha and airport transfers from Dong Hoi, plus tour extensions if requested.
Step 6: Health Update Before Departure
Around 45 days before the tour, you must submit an updated health status. If any medical changes occur (injuries, chronic illness), you must inform Oxalis.
False or incomplete declarations may lead to tour cancellation without refund, as safety is the top priority.
Fitness Requirements for Son Doong Expedition
Son Doong is rated Level 6/6 – the highest adventure level by Oxalis. It is not suitable for inexperienced trekkers, people with medical conditions, children, or pregnant women.
The 6-day journey covers 25 km of forest, dozens of river crossings, and a 90-meter climb up the 45-degree “Great Wall of Vietnam” at the cave’s exit.
Total elevation gain may reach 800 meters, requiring excellent fitness and serious preparation.
Required Trekking Experience
Within 12 months before your departure date, you must complete:
- At least one overnight trekking trip.
- At least two full-day treks (each 8+ km) with varied terrain and 300m+ elevation gain.
Having joined Oxalis’s Hang Va, Tu Lan, or Hang En tours is a plus, and you’ll receive a 10% discount for doing so.
Training Tips
Train consistently for 3–6 months before your trip. Suggested activities:
- Run 5 km in under 50 minutes.
- Climb 10 floors non-stop without exhaustion.
- Hike 5–8 km/day, 3–4 times/week.
- Outdoor activities like mountain hiking, cycling, or swimming.
Important notes
If you misrepresent your health or lack fitness and must quit the tour, no refund or transfer will be allowed. Take your health seriously and prepare accordingly.
Essential Clothing and Personal Gear for the 6-Day Son Doong Cave Expedition Tour
The Son Doong expedition lasts 6 days and 5 nights, so participants must prepare sufficient and appropriate personal clothing and gear. Below is our recommended packing list for your adventure with Oxalis Adventure:
- Long-sleeve trekking shirts (3–4 pieces): Prefer light-colored, quick-dry, moisture-wicking fabric.
- Trekking pants (2–3 pieces): Slightly stretchy, quick-drying, and flexible for movement.
- Camping sleepwear: A comfortable and warm set of clothes for sleeping inside the cave.
- Light jacket: To stay warm during cool weather or at campsite resting areas.
- Hiking shoes: Choose ones with good grip, fast drainage, lightweight, and snug fit.
- Thick socks (4 pairs or more): To keep warm and prevent blisters after long trekking hours.
- Slippers or sandals: To relax your feet at campsites after trekking.
- Small daypack (20–25L): For daily essentials like water, raincoat, camera, etc.
- Dry bag: To protect electronics and clothes when crossing streams.
- Thin grip gloves: For climbing and protecting your hands on rocks.
- Sunglasses, hat, sunscreen: For sun protection during outdoor sections.
- Swimwear: For swimming in underground pools inside the cave.
Other Personal Items
- Personal hygiene items: Choose eco-friendly and biodegradable products (e.g., dry soap, natural toothpaste).
- Power bank: For charging your personal electronic devices like phones and cameras.
- Personal medication: Bring all necessary prescriptions or common-use medicines (e.g., pain relievers, allergy meds, digestive pills).
- Wet wipes: Useful for cleaning up when bathing is not possible due to weather or terrain.
Note: Do not bring unnecessary fashion items. Your luggage should be minimal but complete. Oxalis provides porter service for large luggage—you only need to carry your daypack during the trek.
How to Get to Phong Nha to join Son Doong Cave Expedition Tour
To join the Son Doong Cave Expedition Tour, you need to be present in Phong Nha commune, Quang Tri Province, home to Oxalis Adventure’s headquarters. Tour participants will receive free transfers from Dong Hoi, the capital of Quang Tri, to Phong Nha. Here are the most common ways to get to Quang Tri:
By Plane
This is the most convenient and time-saving option. Book a flight to Dong Hoi Airport (VDH) – the closest airport, located about 45 km from Phong Nha. There are multiple daily domestic flights from Hanoi, Ho Chi Minh City, Da Nang, and Hai Phong to Dong Hoi.
Oxalis provides free airport transfers for all confirmed bookings.
By Train
Dong Hoi Railway Station is a major stop on the North–South railway line. You can board a train from Hanoi, Hue, Da Nang, Nha Trang, or Ho Chi Minh City. Oxalis offers free transfers from the station to Phong Nha for tour guests.
By Sleeper Bus
There are several high-quality sleeper buses that run directly to Dong Hoi from major cities:
- Hanoi: Overnight buses take approximately 9–10 hours.
- Hue: Around 4 hours.
- Da Nang: Approximately 6–7 hours.
Note: If you travel by bus from Hanoi, choose a reputable provider that goes directly to Phong Nha instead of Dong Hoi to avoid extra transfers.
Final Thoughts
The Son Doong Cave Expedition Tour is an extreme adventure—only suitable for those with good physical health and the determination to conquer challenges. In return, you’ll experience one of the world’s most magnificent underground landscapes—a place few people ever reach.
To participate, you must be thoroughly prepared in terms of fitness, bring the right gear, and strictly follow the booking procedures. Proper preparation is the only way to ensure your journey is safe and truly unforgettable.
We hope this guide helps you successfully book and prepare for your Son Doong expedition!