A Similan Islands liveaboard is an affordable way to enjoy Thailand’s best diving – just be prepared to see plenty of other divers in this popular dive location.
Glassfish schooling around coral bommie © Chris Mitchell
The Similan Islands are where to find Thailand’s best scuba diving. A group of nine islands off the west coast of southern Thailand in the Andaman Sea, the Similans have long been revered as one of the most accessible – and affordable – places to dive on a liveaboard boat, typically spending four days at sea and exploring the Similans along with the three dive sites further north – Koh Bon, Koh Tachai and, famously praised by Jacques Cousteau himself, Richelieu Rock.
Manta Ray on the safety stop, Breakfast Bend © Chris Mitchell
The Similans are special to me because, as for many people, it’s where I did my first liveaboard on the MV Dolphin Queen, back in 2003. I did many subsequent liveaboards in the Similans over the following 12 years, but the last time I dived there was back in 2015 on a Thailand – Myanmar liveaboard trip on the Thailand Aggressor.
Glassfish over hard coral © Chris Mitchell
Returning to the Similans five years on, there’s no denying that there is still a lot of magic to diving here. There is so much to see, both in terms of the reefs, the ever changing underwater landscapes, the abundance of marine life and the very likely chances of seeing a manta ray. It really is a special place, especially if you’ve never dived it before. But – you just knew there was going to be a but – the degradation of the reefs over the last 15 years is palpable. Several dive sites have been closed for years to give their corals a chance to recover. There are way too many boats operating in the area. (Indeed, several boats like Panunee and Mermaid have relocated to Indonesia permanently).
Dive buddy in the shallows © Chris Mitchell
Even with the Similan Islands closed six months of the year, from May to October, there is a lot of pressure on the Similan underwater environment. The Similans have essentially become a victim of its own success – it’s affordable and it’s accessible and so everyone can easily go there. So you are very likely going to see a lot of other divers in the water. It’s not a showstopper, but you should manage your expectations accordingly – unlike many places in the Philippines and Indonesia, the Similans is not some remote secret underwater paradise.
Here’s a brief overview of the sites we dived during our Similan liveaboard on the MV Hallelujah in February 2020.
Tuna Wreck at Hideaway Bay © Chris Mitchell
A deep dive to start down to the Tuna Wreck, a deliberately sunk boat intended to create an artificial reef that went a little bit awry. Lying on its side around 26 metres down, the wreck is impressively large and still ship-shaped rather than a pile of twisted metal. Beyond the wreck is steep sloping reef which provides shallower depths to explore. One thing that surprised me on this trip is that we had several dives where the water was distinctly murky green rather than the sun-dappled blue – this first dive was a taste of that.
West Of Eden
Sun on the boulders at West of Eden © Chris Mitchell
One of the most distinctive features of diving in the Similan Islands are the huge boulders that make up the topography of some of the dive sites. These giant granite stones, easily three or four times the height of a diver, are clustered together, creating swimthroughs and sheltered spots for fan corals and other life to take hold. On our dive, the boulders were lit up by the sunlight near the surface, creating some beautiful reflections in the flat calm water.
Breakfast Bend (aka Three Trees)
Soft coral bommie, Breakfast Bend © Chris Mitchell
This site, also known as Three Trees, is one of the hardy perennials of Similan diving – I am pretty sure I’ve dived this site almost every time I’ve been here. The site is basically a gentle sandy slope running down from the island, interspersed with some gorgeous coral bommies which have pink and purple soft corals and bright orange fan corals clustered around them. We then had the best safety stop ever, as while we were gently drifting at 5 metres we were joined by a manta ray which glided straight past us, headed out into the blue, and then came back and unhurriedly circled us a couple more times.
Manta Ray on the safety stop, Breakfast Bend © Chris Mitchell
While mantas are quite frequently spotted on Similan trips, it’s usually at Koh Bon and Koh Tachai, so this a real treat, especially as it was a prolonged encounter rather than a fleeting glimpse.
Glassfish schooling in hard coral © Chris Mitchell
While the other groups on our boats headed to the dramatic big boulder site North Point, we decided to have a nose around Christmas Point, a shallow coral garden. Photo wise, this was a great place to be for wide-angle reef shots (my favourite kind). The profusion of hard corals stacked on each other and covered in hundreds of glass fish makes for a dynamic, ever changing reefscape, especially as the sun came out and the viz was pretty clear. It was the perfect gentle dive to begin the day.
Longnose Emperor Fish feeding © Chris Mitchell
By the middle of day two we were already leaving the Similan Islands proper and heading to the northern sites in the Similan Marine Park, the nearest being Koh Bon. A huge uninhabited granite rock in the middle of the ocean, Koh Bon is most famous as a manta ray hotspot, but there’s plenty of other life here too. There’s three distinct areas to dive – the Bay, the shallower, sandy area from where you can swim to the Ridge, a long submerged finger of rock jutting out along the sandy ocean floor and then the other side of the Ridge, which is densely populated coral garden.
Divers tend to congregate at the ridge as this is where mantas are most often spotted – that said, we saw a manta on our final dive of the trip in the Bay, again quite shallow as with our encounter at Breakfast Bend. We dived Koh Bon a total of 3 times during the trip – once on Day 2 as we headed north – and then twice on Day 4 as the last two dives of the trip on the way home. The site is big enough to need three dives to explore, and few divers will refuse the chance to wait and see if a manta will turn up.
Glassfish on coral bommie © Chris Mitchell
Koh Tachai is one of the other most-anticipated sites of a Similan liveaboard itinerary, but I have always had bad luck diving it over the years – either there’s been terrible viz or super strong currents – or both! Happily, our two dives here were great fun – while the visibility was cloudy, we still got to see the distinct silhouette of a manta sweeping across the late afternoon sun shining down through the water. The site itself was electric – it felt like hunting time was about to begin and huge schools of jacks and rainbow runners ran back and forth across Tachai’s underwater pinnacle, while clouds of glass fish darted back and forth in an endless murmuration around clusters of hard and soft corals clinging on to Tachai’s rocks. It was these dives that finally, finally showed me something of what so many people raved about when they dived Tachai.
Turtle Ledge, Surin Islands
Kayo the dive guide and clownfish © Chris Mitchell
A gentle dive to begin the third day at the Surin Islands. While there is an abundance of hard corals in the shallows here, it was a fairly quiet dive for marine life, although the viz was great – the classic Andaman blues rather than the green we’d seen on quite a lot of dives.
Finger of rock with plate coral © Chris Mitchell
One thing particularly notable at Turtle Ledge were the precarious giant fingers of rock and coral that had evolved and survived over the years.
Dive buddy with soft corals, Richelieu Rock © Chris Mitchell
A horseshoe shaped rock in the middle of the ocean, Richelieu Rock is a safe harbour for all manner of marine life big and small, as well as being resplendent with red and purple soft corals gathered on its limestone surfaces.
As Thailand’s finest dive site, everyone wants to dive it – and so the first of our three dives was a circus of running into other divers around every corner. Strong currents herded various groups into the same area for protection but even so, the sheer amount of people in the water on what is a relatively small site was pretty shocking. It wasn’t helped by a distinct lack of polite etiquette around taking photos or simply paying attention to what – or who – are around you.
Cuttlefish at Richelieu Rock © Chris Mitchell
The two subsequent dives were far more pleasant with calmer waters and less people around, but I got the distinct feeling there was less marine life on the Rock itself and that the soft corals were fewer in number and less of a flourishing carpet of colour than I’d seen in previous years. Hard to say for sure – the visibility was quite murky on all three dives and Richelieu’s colours really explode when the sun can shine upon it.
Dive buddy and octopus, Richelieu Rock © Chris Mitchell
All that said, there was still plenty to see – while the resident huge school of yellow snapper that had hung out inside the horseshoe in previous years had moved on, there were some impressively sized – and scary looking – barracuda implacably cruising amongst divers, while we also saw two cuttlefish amongst the soft corals and an octopus also taking a breather on the back end of the rock.
Koh Bon (final day)
Dive guide over the corals, Koh Bon © Chris Mitchell
While the first dive on Day 2 at Koh Bon was fairly average – viz not terribly good and no big flappy things – the final two dives were beautiful. Not just because of the delight of seeing a fleeting drive-by from a manta soon after we dropped into the shallows, but because the viz was 3D panoramic. At the ridge you could the serrated rocks stretching out into the blue, laid out below us as if we were flying over it. The clear water also let us see just how big the coral clusters had grown on the other side of the Ridge as we drifted over them – serried rows of plate corals that covered a huge area of the site’s sandy slope. It was the kind of dive that, regardless of what you saw, just made you happy to be in the water and see this landscape unfold beneath you.
Similan Island Liveaboard Final Thoughts
School’s out, Breakfast Bend © Chris Mitchell
In conclusion, despite being fed up with the number of divers on some sites and the deterioration of the reefs, I really enjoyed this trip. The Similans as a four day trip are hard to beat in terms of the environments you move through both underwater and above. There’s the dramatic big boulder sites, and then the sloping sand sites, and then the granite towers of Koh Bon and Richelieu.
Hard corals, Christmas Point © Chris Mitchell
There’s a lot of fish life around, beautiful soft corals and the chance to see manta rays and maybe even a whale shark. There’s spectacular sunrises and sunsets over usually flat calm waters overlooking powder white beaches, with warm evenings cooled by sea breezes and cold beer. It’s really hard to argue with. The boat and crew on MV Hallelujah did play a big part of that, as did my guide Kayo and dive buddy Estela and all the other great people I met on the boat. (Hey Sunita and Sudesh!).
My only concern is that if this number of divers and boats continues to dive the Similans with seemingly little regulation or management, there won’t be much worth diving in another 15 years. So – as with the coral reefs everywhere in the world – I’d suggest seeing it sooner rather than later.
Manta Ray on the safety stop, Breakfast Bend © Chris Mitchell
You can see the distance between the Thailand mainland the Similan Islands (all nine of them) as well as Koh Bon, Koh Tachai and Richelieu Rock. You’ll need to zoom in to see them as they are literal specks on the map.
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