Secret Crystal Cave in Kanchanaburi - An Amazing Hidden Gem

There is a hidden cave in Kanchanaburi province where the floor is covered by perfectly formed triangle formations. The cave is tricky to find, takes some effort to climb to, but those triangle crystals are an otherworldly sight.

Kanchanaburi province is famous for its limestone landscape, characterized by dramatic karst formations, caves, cliffs, and rugged mountain ranges. Just think of Erawan National Park! These limestone karsts are often covered in lush tropical vegetation that conceals an extensive network of caves and underground rivers, some of which are home to unique ecosystems and species, like the bumblebee bat.

One such hidden treasure is the Phu Ma Dang Cave, one of the most fascinating crystal caves in Kanchanaburi Province. Known only by the locals, this is the most intriguing crystal cave in Kanchanaburi.

I spent several years living in a village not far from the cave and I visited it with my Thai friends. The cave is so well concealed, you’ll never know it’s there. This is one of the most interesting thing about rural Kanchanaburi – the limestone hills that dominate the landscape here are peppered with caves.

Some of these caves provide shelter for hermit monks (like the Old Abbot’s cave near our village), others are treated as holy sites, and many become tourist attractions, like those in Erawan and Sai Yok national parks. But some, like Phu Ma Dang cave, remain under the radar like true hidden gems.

Phu Ma Dang is located near the top of Nakon Mountain on the main Kanchanaburi – Sai Yok highway and can be reached by a very steep climb through bamboo forest.

Phu Ma Dang Cave in Kanchanaburi- bamboo forrest — Bamboo forest on the way to the cave

The arduous climb might just be why the cave remains virtually unknown to the outside world. As for me, labouring up a steep mountainside for half an hour in 40-degree heat and 90% humidity is part of the adventure. Once you reach the cave, you feel like you deserve to see its magic.

The view from the cave’s entrance is a nice perk. It sweeps over Kanchanaburi countryside of green fields fringed by rolling hills covered in thick forest.

View from Phu Ma Dang cave in Kanchanaburi — View from the cave’s entrance

The coolness of the cave is a welcome relief from the moist heat outside. There is pretty much just one chamber in the cave, but it is quite vast, and thankfully, it hasn’t suffered much damage from local souvenir hunters.

The first thing you’ll notice is that the cave floor, walls, and ceiling are covered with surrealistic crystal formations. Near the entrance, you’ll find the familiar type of limestone stalactites and some shawl formations.

The most striking formations, however, are those known as “pool spar” because they form underwater.

Ornate crystals in Phu Ma Dang Cave in Kanchanaburi — Pool spar crystals

Some of them resemble snow and coral, and others look like crystal ice sculptures. The sheer variety of formations in this virtually unknown cave is incredible. Some areas even glitter with crystaline formations, their intricate shapes catching the faintest light of your flashlight.

Ornate crystals in Phu Ma Dang Cave in Thailand

But it is the floor of Phu Ma Dang cave where things get really unusual. That floor is one of the strangest things I have ever seen.

Unlike most caves, where the floor might resemble the flow of melted wax or be covered by rocky debris, part of the floor of Phu Ma Dang cave is made up of small, irregular triangles. These formations look so precise, you’d think they were hand-cut tiles in a rustic bathroom. But they’re not—they’re entirely natural.

Unusual pool spar triangular formation on in a cave in Kanchanaburi — Pool spar triangles on the cave’s floor

These triangles are also “pool spar” formations, and they occur when mineral-rich water pools on the floor of a cave. If the water remains static long enough, these solid, triangular shapes form as the minerals crystallize. It’s an incredibly rare phenomenon, and it adds an almost surreal quality to the cave.

How to Get to This Secret Cave in Kanchanaburi

Nakon Mountain in Kanchanaburi — Nakon Mountain and entrance to Phu Ma Dang Cave

The cave is virtually unknown outside of the few surrounding villages, so you will have to visit it independently. It is located along Hwy 323, which connects Kanchanaburi to Sai Yok.

From Kanchanaburi, head to Chia Tai Farm. About 34km from town, you will see rows of greenhouses on your right – this is Chia Tai.

Another 2km down the road, you will come to a Caltex petrol station on your left. This is a good place to ask the local shop attendants to point out the Nakon Mountain. It is part of a chain of towering hills on the right side of the highway.

Once you get to the base of the mountain, look up to locate the cave near the top (refer to the top image in this post). There is a faint path you can follow, but generally, just head up.

Know Before You Go

Make sure to take plenty of water with you. The climb is hard work, and the heat will be your worst enemy. And, of course, bring a torch – the cave is pitch black.

Thais do the climb in flip-flops, as did I. Had I known what I was getting into, I would’ve opted for more sensible footwear. So, you can do it in thongs, but you’ll be wishing the whole way up that you wore a pair of sneakers instead.

And it goes without saying, don’t give into the temptation to break off any of the crystals to take home as souvenirs.

Why It’s Worth the Effort

Phu Ma Dang Cave is more than just a cave; it’s a glimpse into the geological wonders of Kanchanaburi. The combination of its surreal crystal formations, its rare triangular floor, and its hidden location makes it a truly special place.

Kanchanaburi Province has no shortage of incredible sights, from the waterfalls of Erawan National Park to the historic sites along the River Kwai. But if you’re looking for something different, something that feels like a personal discovery, Phu Ma Dang Cave is where you’ll find it. So lace up your boots, pack your torch, and get ready to uncover one of Kanchanaburi’s best-kept secrets.