Diving the Similan Islands, Thailand

After my first liveaboard in 2016, I was hooked. Eat, sleep, dive, repeat. For me, this means closing my eyes and dreaming of fish and all the amazing things I saw that day, and waking up to experience it all over again for days on end.

About the Similan Islands

The Similan Islands are 11 islands located about 70 kilometers off the coast of south coast of Thailand, specifically the Phang Nga Province. It’s only possible to visit mid-October to mid-May each year because outside of those months, the seas are too rough and the islands are closed for conservation, which gives the reefs a chance to regenerate and be protected against overtourism. When the season is right though, the islands are really a diver’s dream.

The reefs are full of dramatic boulders, stunning coral gardens, and visibility that often stretches 20 to 30 meters, and the Similan Islands are generally considered to be some of Asia’s best diving. There’s also chances of seeing manta rays, whale sharks, and everything from ghost pipefish to nudibranchs!

Planning your trip …

Liveaboard trips in the Similans range from 3 to 7 days and are available for all certification levels, though advanced divers will get the most out of deeper or drift-heavy sites. Prices vary depending on the boat’s comfort level—budget-friendly to luxury—but generally include accommodation, meals, tanks, weights, and sometimes gear rental.

The best visibility and calmest seas are typically found from January to April. It’s wise to book ahead, especially around holiday periods as it can be pretty popular.

Getting there …

By Air:
The closest major airport is Phuket International Airport (HKT), which has direct flights from Bangkok, Chiang Mai, Singapore, Kuala Lumpur, and many other Asian hubs. From there, it’s a scenic 1.5 hour drive north to Khao Lak. Most diving and liveaboard operators offer transfer services to and from Phuket International Airport or hotels in Phuket or Khao Lak which makes the process much easier.

If you’re flying in and out of Bangkok, remember that there are 2 airports (DMK and BKK) so make sure you check the airport code when you’re booking! Especially if you’re flying out of Bangkok the same day as getting between these airports can take at least an hour driving when traffic is bad. I made a mistake when booking my flights back because I foolishly booked my Phuket - Bangkok flight to arrive in BKK, but my Bangkok - Sydney flight a few hours later was departing from DMK so I had to rebook my Phuket - Bangkok flight to arrive at the same airport and make sure I had enough time to catch my final flight home.

By Land:
If you're already in Thailand, buses and minivans run regularly to Khao Lak from places like Phuket Town, Krabi, and Surat Thani. It’s also possible to hire a private transfer if you prefer a more direct and comfortable option.

Before You Board:
Most liveaboard departures are in the late afternoon or evening, so you may wish to arrive a day early to rest, have time to check out the surroundings and avoid any last-minute travel hiccups. Khao Lak has plenty of accommodation options and dive shops if you need to pick up any last-minute supplies.

Make sure to bring your certification cards/logbook, and if you're planning to dive deeper or explore advanced sites like Richelieu Rock, having your Advanced Open Water certification is a big plus (some boats even offer the course onboard if you want to level up during your trip).

I did my nitrox certification on this dive and it was very easy and straightforward. It meant I got to enjoy the deeper diving for a little longer so there was more time to spend enjoying the marine life. Doing 4 dives a day on a liveaboard can also get pretty exhausting but the nitrox helped with keeping the tiredness at bay.

What To Bring:

Other than the usual diving gear (if you’re not renting it), I’d recommend bringing a good book to enjoy during your surface intervals, reef-safe sunscreen, sea-sickness tablets (even if you think you don’t need them), a hair mask and brush if you have long hair, and a cover up to keep you safe from the sun.

These photos are taken from Nai Yang beach in Phuket. I spent the day here before I had my transfer pick up to take me to the boat and there were lots of wonderful food stalls and coffee shops.

What is a liveaboard, and why do it …

A liveaboard is essentially a dive boat that doubles as your accommodation, restaurant, and dive center all in one. It allows you to reach more remote sites, dive early in the morning and after dark, and usually it means the reefs and diving are better because they are less visited meaning they are less damaged.

I used liveaboard.com to research the best liveaboards for me based on my dates and budget. In the end, I joined a 3-day, 4-night liveaboard departing from Khao Lak on Manta Queen 2 which was a bit more budget compared to other options but still very comfortable. Our itinerary included a mix of the Similans, Koh Bon, Koh Tachai, and the legendary Richelieu Rock. And yes—it lived up to every bit of the hype.

These were our wonderful chefs, who made the best Thai food for us. They were constantly working hard so that every morning, there would be coffee and snacks before our first dive, endless snacks through out the day and warm pandan teas ready for us when we got out of the water, lunches and dinners.

Conservation and responsible diving

The Similan Islands are a protected marine national park, and it’s vital that we respect the rules. That means no touching marine life, maintaining good buoyancy, and avoiding reef-damaging fins or gloves. Operators here are generally excellent about safety and sustainability, but it’s always worth asking about their practices before booking.

Some boats participate in reef clean-ups or citizen science projects like submitting photos to Manta Trust or Whale Shark ID programs. Getting involved adds another layer of meaning to the experience.

The diving …

Day 1: A Gentle Introduction

After we boarded the boat and found our rooms, we did a gear set up and were introduced to the boat crew and each other. We were also given a briefing on the morning’s dive site and what to expect, and then the ritual of setting of firecrackers at the bow of the ship was done to scare off any evil spirits from the ship before we cruised overnight to Koh Bon in the Surin Islands, one of the northernmost islands in the archipelago.

Day 2: Koh Bon, The Dome & Tachai Reef

Our first dive was a check dive at Koh Bon Pinnacle —an easy descent onto a sloping reef. Despite being one of the more mellow sites, it was teeming with life: parrotfish munching coral, blue-spotted stingrays nestled in the sand, huge schools of batfish, hunting moray eels, blue eyed trevally and more. If you’re lucky, you might see manta rays here as it is a cleaning station but we sadly missed them on our dive.

One of the joys of liveaboard diving is the rhythm: dive, eat, nap, repeat. After the first dive, we returned to the boat for a warm breakfast, debriefed, and prepared for the next dive. Each day included three to four dives, including at least one night dive, depending on conditions and energy levels. While you’re certainly not expected to dive every single time, it’s not a cheap trip so I made sure to get the most out of it. That said, it’s always safer to skip a dive if your’e not feeling 100% right.

At The Dome, we descended onto a GIANT baraccuda and school of batfish. There were some reasonably strong currents but our dive kept us in the safe parts of the water. There were so many fish you could actually hear them.

We had a night dive at Tachai Reef where we could see hunting lion fish and a hunting nurse shark but the best part of the dive was the bioluminescence. I swam backwards for most of the dive splashing like a child so I could see the green particles flashing in the water.

Day 3: Richelieu Rock x 3, Koh Bon and Bonson Wreck

We kicked off the day with the kind of site most divers dream about: Richelieu Rock. It’s so well loved we ended up diving it 3 times but that also meands everyone in the area ends up diving it a few times so there’s as many people as there are fish on some days. While I definitely understand the hype, it can get a bit crowded and you spend a lot of energy making sure you don’t lose your dive guide and buddy in the sea of people.

That said, each dive revealed something new. In the morning, soft corals were light up with golden light, and schools of glassfish swirled around the horseshoe-shaped pinnacle like a living cloud. Ornate ghost pipefish hovered near purple sea fans, and a harlequin shrimp played hide-and-seek in the cracks. We kept one eye on the blue—hoping for that shadowy whale shark silhouette. No luck this time, but the sheer biodiversity made every minute feel electric.

After lunch, we cruised back toward Koh Bon for an afternoon dive. The current was stronger than earlier in the trip, but the energy brought in the action. Trevallies, giant morays, and the ever-hopeful scan for mantas kept us alert and grinning behind our masks.

To wrap up the day, we descended on the Boonsung Wreck, an old tin dredger that now rests broken but thriving on the seafloor. Despite the low visibility typical of the site, it was absolutely teeming with life: pufferfish, lionfish, scorpionfish, and dozens of honeycomb moray eels peeking from every crevice. It felt otherworldly—rusting metal blanketed in marine life, lit by the soft rays of a setting sun.

We surfaced with just enough light left to watch the sky turn pastel pink from the sundeck—tired, salty, and absolutely content and reminded of why we fell in love with diving.