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The Artificial Reefs of Koh Tao

Artificial Reefs are becoming more and more popular as divers worldwide become more environmentally aware. Artificial dive sites provide homes/shelter/safety for a variety of marine life, and also alleviate the pressure from regular dive sites, which is especially important in heavily dived areas. Koh Tao has been developing and promoting artificial dive sites for a number of years, and Master Divers has been actively involved in assisting with the construction and maintenance of some of these too. Our favourites on Koh Tao are:


As the name suggests, Junkyard is an artificial reef made out of, well… junk! Not your regular sort of everyday trash, but lots of larger, bulkier items that would otherwise be difficult/expensive/environmentally unsound just to throw in landfill and forget about! There’s a pickup truck, a Sydney Harbour Bridge, a mini gym, a windmill, a pyramid, several cage structures on which transplanted coral grows, long metal archway tunnels – great for practicing swim-through buoyancy techniques, and even a sculpture made out of old toilets – which as you can imagine has been the backdrop to many an ingenious photo moment!

A Diver Swims Beneath the 'Coconut Monkey Tree'
A Diver Swims Beneath the ‘Coconut Monkey Tree’


In and among all of these man-made monuments you’ll often find juvenile Longfin Bat Fish, Puffer Fish and Box Fish of pretty much every shape, size and species, a few varieties of File Fish (most of which cannot be found at any other dive site around the island), Saddleback Anemone Fish, and often some Crabs & Shrimp too. Night dives to Junkyard are also pretty impressive. Giant Hermit Crabs wander to and fro and Blue Spotted Sting Rays also come out to hunt along the sandy bottom. If you’re lucky, you may even spot some Pleurobrach, a type of marine slug. Nothing unusual there you may think, especially if you’re well versed in your Nudibranchs. Pleorobranchs, however, are much bigger – normally dwarfing their Nudibranch counterparts by a ratio of over 100-1!

Juvenile Batfish
Juvenile Bat Fish


Bio Rock

BioRock was where it all started in terms of artificial reefs on Koh Tao. A collaboration between marine biology students from mainland universities, a number of dives schools worked together to sink Koh Tao’s first official artificial. Bio Rock – or Hin Fai, as it is also known – is a large dome structure with smaller satellite dome structures and boulders surrounding it. The domes are used as a base structure on which to attach transplanted corals. The special and unique feature however, is that the dive site is fed by an electrical current from the land in the form of cables, which encourage and hasten coral growth – the idea being that corals grown here can be transplanted to other dive sites on the island where the health of the reef has declined.

In his 2012 paper focusing on Coral Reef Rehabilitation, Gerianne Terlouw noted “We find that corals on the Biorock structure grow up to 80% faster than corals in other reef areas when conditions are optimal.”


BioRock_Koh Tao_Ayesha_Cantrell_003
Corals Growing on the Dome Structures


HTMS Sattakut

As artificial reefs go, shipwrecks are one of the most popular, and we are lucky to have the HTMS Sattakut on our doorstep. This 49metre long naval war ship sits in 20-30metre depth region, so is perfect for fun divers (if qualified to dive below 18metres of course!), wreck adventure dives and wreck and deep specialties alike. Sitting upright on her flat bottom with impressive cannon style guns at the front and rear, a circular conning tower, and numerous port holes to peer through, she’s an easy wreck to explore. Over the years we’ve documented this wreck in our blog a few times. You can read more about her and research more links, from our post on the sinking of the Sattikut here.

Peeking Through a Porthole
Peeking Through a Porthole


Around the wreck you’ll likely spot large Groupers, Andaman Sweetlips, and schools of Rabbit Fish as well as Big Eye and sometimes even Giant Trevally. Schools of juvenile fish such as Yellow Tail Barracuda often inhabit some of the rooms inside the wreck, and use their artificial home as protection against larger predators. In crevices hiding under the wreck you can often see Jenkins Whip Rays too.

Giant Grouper


Buoyancy World

Not quite Disney World, but for inquisitive divers who enjoy seeing something a bit different on their dives, Buoyancy World definitely provides a fun factor. Located next to Twins, and easily navigable within a dive at Twins itself, Buoyancy World comprises of a number of structures designed to aid with buoyancy training. Because of this it is regularly visited on PADI Advanced Open Water training dives and PADI Peak Performance Buoyancy Specialty courses. Another collaboration between a few Koh Tao dive centres, it has hoops and squares, a mini maze, concrete rings and even an octopus to help hone your buoyancy, trim and swim-through techniques. It also has some additional structures such as a shark, turtle, some phone box-like structures and a host of concrete blocks that attract marine life and curious divers alike.

Buoyancy_World_Koh Tao_Ayesha_Cantrell_003

Buoyancy_World_Koh Tao_Ayesha_Cantrell_001


This list is by no means extensive, and several other dive sites now have artificial sections too. You’ll find an extensive concrete block site at Hin Ngam, ‘Utopia’ structures at Tao Tong, reef balls (and even a couple of motorbikes) at Tanote Bay, and many more besides. Interested in diving some artificial sites? Let us know and we’ll be only too happy to schedule some for you!

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