• By: admin
• Oct 05, 2026
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There’s a jungle growing inside this cave. And you’ll have to wait until 2028 to see it.

Hang Son Doong, in central Vietnam, is the largest cave passage on Earth. It’s so big it has its own weather, its own river and its own forest. It’s also one of the hardest places in the world to get into.

Why Son Doong is so special

Inside, the main passage is so tall that a skyscraper could fit in parts of it. In two places the ceiling has collapsed, letting sunlight pour in. Where the light lands, a real jungle has grown, with trees reaching up toward the holes in the roof.

Clouds form inside the cave because the air underground is a different temperature to the air outside. Explorers camp next to underground rivers and wake up to mist drifting through the chambers.

A cave hidden until recently

A local man, Hồ Khanh, found the entrance in the early 1990s while sheltering from a storm in the jungle. He couldn’t find it again for years. In 2009, he led a British caving team back, and they realised it was the biggest cave passage ever found.

It sits inside Phong Nha-Ke Bang National Park, a UNESCO World Heritage Site full of caves.

Why it’s in the news

• Only about 1,000 visitors a year are allowed in.
• Groups are capped at 10 guests, with around 100 departures a year.
• Travellers from more than 70 countries have done the expedition.
• Every tour for 2026 and 2027 is fully booked. Bookings for 2028 are now open.

One company, Oxalis Adventure, runs all the official expeditions.

What the expedition is like

The trip lasts 4 days and 3 nights. You hike through jungle, cross rivers, and abseil and climb with ropes inside the cave. You sleep at campsites underground, with a team of guides, porters and cooks.

It’s hard work. You need good fitness, and the operator checks that you’re ready before confirming your place. It’s also expensive, costing several thousand US dollars, because the group is tiny and the support team is large.

Can’t wait until 2028?

Phong Nha has lots of other caves you can visit right now:

• Paradise Cave: a huge, easy cave with a boardwalk and beautiful rock formations.
• Phong Nha Cave: explored by boat along an underground river.
• Hang Én: one of the world’s biggest caves, done as an overnight trek with camping by a lake inside.
• Tu Lan caves: swim through flooded caves on a multi-day adventure.

How to get there

Fly to Dong Hoi, the closest airport, then drive about an hour to Phong Nha town. From the Gulf, connect through Hanoi or Ho Chi Minh City.

Tips

• Book early. Very early. Years ahead for Son Doong.
• Train before you go. Hiking with a pack and climbing will feel much easier.
• Do a smaller cave first. Hang Én or Tu Lan are great warm-ups.
• Go in the dry season. Expeditions stop when the rains raise the rivers.

Your challenge

How many people can visit Son Doong each year? About 100, about 1,000, about 10,000, or unlimited? Answer on my post at @explor_shan.

Then try the AI prompt challenge and create your own jungle inside a cave.

FAQ

Is Son Doong the biggest cave in the world?
It has the largest single cave passage by volume, which is why it’s often called the world’s biggest cave.

Can I visit without a tour?
No. Entry is only through the official expedition.

Do I need caving experience?
No, but you do need good fitness and a head for heights.

Would you wait two years for this? Save it for your 2028 list.

Explore with me every day. Follow @explor_shan on Instagram for the daily challenge, and comment EXPLORE on any post to get the guide in your DMs.