🌍 When Stones Tell Stories – The Geological Origins of Khao Sok and the Islands off Khao Lak
- Stephan Werner
- 3 days ago
- 4 min read
Introduction – If Stones Could Speak
Imagine the rocks and islands off Khao Lak could talk. They probably wouldn’t start with a polite “hello” but with a deep rumble carrying millions of years of Earth’s history. Some would tell tales of fire and lava, others of water that shaped them. ☺️
Sounds a bit like science fiction? It is – except it’s not made up, it’s the real history of our planet. And right here, off the coast of Khao Lak, you can read this story like an open book: in the granite islands of the Similan Islands, the towering limestone cliffs of Khao Sok National Park, and the coral foundations of the Surin Islands.
Today, let’s explore these chapters of geological origins – and as for the flora and fauna that joined later, stay tuned for Part Two on September 15, 2025.
Geological Origin: The Similan Islands – Ancient Granite Rising from the Sea
The Similan Islands are made of ancient granite rocks (Granitoide), uplifted by tectonic forces over millions of years. Think of them as giant natural building blocks, polished and sculpted endlessly by wind, weather and waves. Link to our Tour Similan Islands.
Length: approx. 24 km
Width: up to 7 km
Highest point: around 244 m
When you approach by boat, the rocks rise from the sea like elephant backs – so bizarrely shaped that you could swear an artist carved them. And yet: all nature, all real.
👉 Travel tip: The rocks at Donald Duck Bay aren’t just a photo magnet – they’re a little time machine back into Earth’s geological past.
H2: Koh Bon – The Little Sister with Character
A few kilometers north of the Similans lies Koh Bon, an island that looks tiny at first glance but is geologically far from insignificant.
Length: 1.5 km
Width: 500 m
Highest point: about 80 m
Born from volcanic activity, refined by erosion – Koh Bon today is a quiet geological gem, framed by turquoise waters and a proof that size isn’t everything!
H2: Koh Tachai – the “Maldives of Thailand”
The very name Koh Tachai already sounds mysterious. With its long stretches of dazzling white sand, it has rightfully earned the nickname “the Maldives of Thailand.”
Length: approx. 12 km
Width: 2.5 km
Highest point: about 250 m
The granite base tells of ancient geological forces, while erosion and sedimentation shaped the island over millennia. Stand here and you feel how land and sea have been playing together for ages – and the result? Pure beauty.
👉 Visiting Koh Tachai? Currently (as of September 1, 2025), visits are only allowed by liveaboard diving boats. Landing on the island itself is restricted to protect the ecosystem. If you’re interested, get in touch about a guided dive safari near Koh Tachai.
The Surin Islands – Where Granite Meets Coral
The Surin Islands, north and close to the Myanmar border, are not only stunning landscapes but geologically fascinating.
Length: approx. 15 km
Width: 8 km
Highest point: about 346 m
Here, ancient granite rocks meet millions of years of coral deposits – like two chapters of the same book. One written deep within the Earth, the other composed directly in the sea.
Khao Sok National Park – Cathedrals of Limestone
Anyone who visits Khao Lak and only sees the beaches has missed half the story. Inland, you’ll find the dramatic karst mountain range (Karst topographia) stretching from Phang Nga up to Surat Thani.
Size: 739 km² (just the park itself; the mountain chain extends far further)
Highest peak: up to 960 m
These limestone formations are the remains of an ancient coral reef dating back more than 250 million years. Today, the cliffs rise steep and sheer like stone cathedrals – nature’s very own skyline.
Weather Impact – The Karst Mountains as Climate Regulators
The karst cliffs are not just visually striking – they’re also climate engineers. Moist monsoon clouds from the Andaman Sea build up against these walls, releasing rain that sustains one of Thailand’s greenest regions. Without this natural weather barrier, Khao Sok wouldn’t be what it is today.
Cheow Lan Lake – A Jurassic Park Setting
At the heart of this landscape lies Cheow Lan Lake, created in the 1980s as part of a dam project. And while technically artificial, it looks as though it belongs to another era.
Surface area: approx. 165 km²
Length: up to 20 km
Depth: up to 90 m
Jagged limestone peaks rising dramatically from the water make the scene look straight out of Jurassic Park. Visitors often say they feel like a pterosaur could swoop down at any moment.
👉 My tip: Spending a night in one of the floating bungalows here isn’t just an overnight stay – it’s a journey back into Earth’s ancient past. Tourlink: Cheow Lan Lake Overnight Trip.
Conclusion – A Vacation in Geological Superlatives
From granite islands in the sea to limestone cathedrals in the rainforest – the region around Khao Lak is a geological adventure like no other. Each island, each rock, and each mountain is a chapter in a story written over millions of years.
And because every story has more than one part: On September 15, 2025, we’ll dive into the flora and fauna that thrive in this ancient setting – from tiny plant marvels to giant creatures of old.
👉 If you’re curious to experience these wonders yourself, have a look at our tours – we’ll take you right into the heart of this landscape.
Note: Some of our articles are created with the support of modern AI tools – however, every line is personally reviewed, enriched, and adapted by us. This way, we combine technology with real on-site experience. The title image was also created with AI.
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