unlight always pours into Hang En, but beams like this only exist from December to March. American Ryan Deboodt, who has photographed Son Doong 10 times, explained how he shot this image.
“On this morning, my friend Thanh and I woke up to a cloudy sky. We decided to stay behind, hoping that the sun would break through. We waited and waited. Eventually the clouds broke, and the glorious sunbeam poured through the entrance. I ran around like a maniac for the next 15 minutes capturing as many photos as I could.”
The journey continues through Hang En, back into the jungle…
… towards the relatively small entrance to Son Doong cave, an attribute which helped keep it hidden for so long.
Greeted by a 200-foot drop, trekkers descend into Son Doong using ropes and harnesses. Technical rappelling experience isn’t required.
“It’s not just the size that makes Son Doong remarkable, it’s the beauty,” said Howard.
Temperatures are cooler at the bottom of the cave, which typically holds steady at 73 degrees F, give or take a degree or two.
Son Doong’s size is owing to two main factors: the river that runs through it, shown above, and the fault line upon which it sits, shown below.
Staying dry is not an option on this trek; trekkers cross the river two times while in Son Doong.
The size and features of Son Doong make it popular with travelers, filmmakers (notably, as the home of King Kong in 2017’s “Kong: Skull Island”) and world-class spelunkers.
“Spelunking is an American term. The rest of the world calls it caving,” said Howard.
The cave is estimated to be 2.3 million years old — relatively young considering the surrounding limestone is 400 million years old.
This giant stalagmite is called the Hand of Dog.
“A woman on our original expedition asked if she could name it. She shouted ‘The Hand of God,’ and the lad who wrote it down wrote ‘Hand of Dog’ instead. We didn’t know it was going to be famous, so some names are a bit weird,” said Howard.
No part of the cave is flat but for the campsites, as evidenced here through “Fossil Passage” where 350 million-year old white fossils stand out against the dark limestone.
Ahead is one of Son Doong’s greatest assets – the first of two dolines, or sinkholes …
… which let mesmerizing beams of light penetrate the cave.
Son Doong is so big, it has its own weather system. Sun from the doline heats the river water, which forms clouds within the cave.
The second day of the trek ends at the bottom of the doline, where travelers can bathe in a lake a short walk from the campsite.