Scuba Diving Thailand’s Colorful Similan Islands

Nudibranch Slug Similan Thailand
Colorful Nudibranch Slug
Similan Islands, Thailand

With a simple wave of my hand, glowing trails of green pixie dust materialized in the dark water. Had I become a wizard? Did someone slip me some something?

Nope. I was just on a 3 day live-aboard scuba diving trip around the Similan Islands with Wicked Diving. Hovering weightlessly in a pitch-black abyss conjuring up spells like Harry Potter!

This was my fourth scuba dive of the day. A night dive. The phenomenon I was witnessing is called bioluminescence. Microscopic plankton that can produce light in the same way a firefly does.

Waving my handset them off — creating magic dust in the darkness.

Similan Islands Thailand
Beautiful Similan Islands

Similan Island National Park

Located about 30 miles off Thailand’s West coast in in the Andaman Sea, the Similan Islands have been a protected national park since 1982.

The park originally included 9 islands, but 2 more have been added for a total of 11. They are covered with granite boulders, ironwood & gum trees, and some include small picturesque white-sand beaches.

But the real reason most people visit is not to lay on the beach, but to snorkel and scuba dive the 5000-year-old reefs and boulder fields around the islands.

The sea here is known for it’s amazing visibility, and the underwater wildlife is abundant.

Diving Similan Islands Thailand
Live-Aboard Similan Island Diving

Live-Aboard Scuba Diving

To visit the islands, you can either jump on a speedboat and spend a day at the beach, or book a multi-day scuba diving adventure living on a boat. Common scuba trips last 3 or 6 days.

I was on a mission to swim with Whale Sharks after readers voted for it. So I booked a 3-day dive trip. It would be my very first live-aboard scuba diving experience.

Our boat, the 23 meter (75 foot) M/V Mariner, is normally capable of holding 20 guests in 10 small rooms with 2 bunks each. Seems I lucked out though, as there were only 5 of us! I had a whole cabin to myself.

With three bathrooms, hot-water showers, air conditioning, and a sun deck full of hammocks, this boat was pretty damn nice.

Similan Islands Live-aboard Boat Thailand
My Floating Home for 3 Days

New Friends

Accompanying me on this journey were 4 other travelers. A Canadian in the US Army on leave from Afghanistan, a former Navy officer exploring the world after completing his service, a middle-aged Brit who sold his home to travel the world, and a Scottish woman who’d saved up & quit her job to do same.

Vagabonds the whole lot of us.

A local Thai crew led by Captain Wit kept the ship on course, running smoothly, and above water.

Mountains of delicious Thai food was prepared by two ladies, P’da and Tik. We were supplied with 4+ meals per day.

The rest of the crew was made up of Dive Masters and Dive Masters In-Training from all over the world. Norway. Spain. Canada. United States. Plus two young Burmese refugees training to become Advanced Divers! An eclectic bunch for sure.

Boat Kitchen Thailand
P’da Prepares Yet Another Tasty Meal

Daily Dive Routine

To start the adventure, firecrackers were set off at the front of the boat to ensure safe passage. We slept as the ship motored over to the islands in the middle of the night.

Our morning began with a light breakfast of toast, fresh fruit, and coffee. Then the diving began. The rest of the trip pretty much looked like this:

  • Dive. Eat.
  • Dive. Eat.
  • Dive. Eat.
  • Lay in the sun.
  • Have a beer.
  • Sleep.
  • Repeat.

Not a bad way to spend 3 days!

Scuba Diver Similan Islands Thailand
I ♥ Scuba Diving
Trigger Fish Similan Islands Thailand
Aggressive Trigger Fish

Sea Fan Similan Thailand
Amazing Red Sea Fan
Moray Eel Similan Thailand
Creepy Moray Eel

Incredible Underwater Life

Before this, I’d only dived about 10 times. With a total of 9 dives in 3 days on this trip, I was almost doubling my scuba experience.

I encountered all kinds of new alien creatures and landscapes that I’d never seen before too.

Shape-shifters that could morph into their surroundings in the blink of an eye. Candy-cane striped lions full of poison. Rocks with eyes. Fat ugly worms the size of your arm.

Vibrant multicolored vegetation gently moving with ocean currents. A city full of underwater boulders as big as buildings.

Coral Crab Similan Thailand
Colorful Coral Crabs
Hawksbill Sea Turtle Similan Thailand
Hawksbill Sea Turtle
Soft Coral Similan Thailand
Soft Coral Cave

Protecting the Reef Environment

Coral reefs are having a hard time all over the world. Many believe global warming, overfishing, and chemical runoff is to blame. In 2010 the ocean suddenly warmed up around the Similan Islands, killing off the fragile bacteria that gives coral it’s color.

This phenomenon is called coral bleaching. If warm water conditions last for too long, the coral eventually dies.

Coral health around Similan has improved but the reef is still recovering. In fact 2 of the islands were closed off to divers in order to let the area flourish again. One of our dive sites had just re-opened after 2 years of being off-limits, so that was a treat to see.

Spotted Lion Fish Similan Thailand
Poisonous Spotted Lionfish
Parrot Fish Similan Thailand
Funny Parrot Fish
Nudibranch Slug Similan Thailand
Nudibranch Sea Slug with Eggs

Minimizing Impact

Wicked Diving does its part to help minimize the effects its divers have on the reef. All soaps and shampoos on board are organic. Towels and linens are never bleached. Human waste is disposed far away from any reef in the middle of the ocean.

Every year dive instructors team up with the National Park Service to help clean up the islands above and below the water.

The boat’s kitchen doesn’t serve fish either. While I was initially kind of disappointed, it actually makes perfect sense. We are all there to enjoy the company of our underwater friends, not eat them!

Ethical diving practices are important if we want future generations to enjoy the magic of the underwater world.

Giant Boulders Similan Thailand
Building-Sized Boulders
Scorpion Fish Similan Thailand
Camouflaged Scorpion Fish
Yellowfin Snappers Similan Thailand
School of Yellowfin Snapper (Credit: Jade Fougler)
Sea Star Similan Thailand
Vibrant Sea Star

No Whale Sharks, But…

My mission was to swim with whale sharks. But they didn’t feel like showing themselves. Neither did the giant manta rays that often call this area home.

That didn’t stop me from having some of the best diving experiences I’ve had yet!

Highlights included the magical bioluminescent plankton, stumbling onto a pair of octopi trying to mate, 4 different sea turtles on one dive, big colorful sea fans, tiny art-project-worthy nudibranch slugs, and giant underwater canyons made from boulders the size of homes.

Plus warm, clear water that enabled me witness & photograph it all.

Red Octopus Similan Thailand
Sneaky Red Octopus
Spotted Puffer Similan Thailand
Blue Spotted Pufferfish
Wicked Diving Similan Thailand
Underwater Sign Language

Scuba Diving Addiction

Every time I go diving I’m amazed at how incredible the underwater world is. And how big. There is always something new to learn about and see down there.

Floating weightlessly through an alien landscape full of, well, aliens, is something I don’t think I’ll ever get tired of. It’s probably as close as I’ll get to experience the wonder and discovery of space travel.

On my current quest for the best adventure travel activities in Thailand, diving the Similan Islands is definitely a top contender.

Watch Video: Diving Thailand’s Similan Islands

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(Click to watch Diving Similan Islands – Thailand on YouTube)
Travel Planning Resources for Khao Lak, Thailand
Company: Wicked Diving
Cost: $595 USD (3 Day Trip)

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Recommended Guidebook: Lonely Planet Thailand
Suggested Reading: The Other Side Of Paradise


I hope you enjoyed my story on scuba diving Thailand’s colorful Similan Islands. Here are some wanderlust-inducing articles that I recommend you read next:

Are you a scuba diver? Ever dived in Thailand? Any questions? Drop me a message in the comments below!


Hi, I’m Matthew Karsten — I’ve been traveling around the world for the last 10 years as a blogger, photographer, and digital nomad. Adventure travel & photography are my passions. Let me inspire you to travel with crazy stories, beautiful photos, and money-saving travel tips.
Matthew Karsten
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