Diving & Snorkeling Koh Haa

Mu Ko Lanta National Park

The Mu Koh Haa Yai archipelago, also known as 'Koh Haa' is a group of 6 islands lying around 25 km to the south west of our office at Castaway Resort here on Lanta. ('Mu Koh' means 'group of islands' in Thai)

We love diving Koh Haa due to the usually good visibility, wide range of underwater geology, extensive coral reefs and diverse marine life. It's also one of the most popular diving destinations in southern Thailand.

Diving Koh Haa with Dive & Relax

The name Koh Haa Yai literally means '5 islands and the big one', with Koh Yai being the 'big island' (we normally call it Koh Haa Yai) at the west of the archipelago, and the other 5 islands making up the remainder of this diving and snorkeling paradise.

Each of the 6 Koh Haa islands are quite different, with most being too big to fully cover in a single dive.

This means that we actually have 12+ dive sites around these wonderful islands and we recommend that divers try to make at least two Koh Haa dive trips during their stay on Koh Lanta.

Diving Koh Haa One

The most northerly of the Koh Haa Yai islands is Koh Haa One, with a dramatic west side characterised by steep walls and huge rocks, and a more shallow east side, a mix of wall and sloping reef.

Whale Shark at Koh Haa with Dive & Relax, Koh Lanta

At the east side of Koh Haa One, a large rocky ridge runs from the edge of the island into the deeper water of the north east, creating a long coral encrusted finger visible from the surface, and teeming with life.

Koh Haa - The Chimney

At the south west edge of Koh Haa One lies a series of swim throughs and caverns known as 'The Chimney', which is one of the highlights of diving the Koh Haa islands.

With several shallow entrances, a large, central chamber around 8 - 9m, an exit around 17m, and another shallow exit into the 'fish bowl' some parts of The Chimney can get a little narrow in places making it suitable for more experienced divers.

Dive The Chimney at Koh Haa with Dive & Relax

At the bottom of The Chimney lies a dense garden of white and lilac soft corals around 20 - 22m where the occasional turtle is found, along with stingrays, snapper, trumpet fish and many others.

Giant chunks of rock, fallen from the island above, lie in the sand to the south east of The Chimney - check the deep cracks in these boulders for huge snapper, grouper, and other species sheltering from the divers.

For the macro underwater photographer, countless nudibranchs, tiny crabs, shrimp, seahorses and ghost pipefish are just some of the many species to be found around the wonderful island of Koh Haa One.

Snorkeling Koh Haa One

The south and east parts of Koh Haa One are best for snorkeling, especially over the shallow finger ridge to the east.

The south face of the island provides the best shelter from any possible winds from the north east, with plenty of coral and marine life to see in the shallow water right up to the sheer rock face of the island.

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Koh Haa One Map - Dive & Relax

Koh Haa One Map

Koh Haa One
Visibility: 15m - 30m +
Level of Diving: All Levels
Snorkeling: Yes
Depth: 3m - 35m +
Journey Time: 25 - 35 mins

Check out our high season dive trips and PADI courses.

Diving Koh Haa Lagoon

The famous Koh Haa Lagoon comprises three islands, sometimes known as islands Two, Three and Four, however each has a traditional sea gypsy name. For example, Koh Haa Two has been called Koh Jepun, or 'Japanese Island' by local fishermen for as long as they can remember.

Diving Koh Haa Lagoon with Dive & Relax

These three central Koh Haa islands are connected in the middle by a shallow, sandy lagoon littered with thousands of corals, dozens of anemone beds, and home to hundreds of different marine life species.

There is a huge abundance of marine life around all three of the islands which make up the Koh Haa Lagoon, and how you dive these areas will depend very much on the experience of your group, air consumption, currents, etc.

Diving Koh Haa Two & Four

Mooring up in the Koh Haa Lagoon allows us the chance to dive both in and around the Lagoon, and also around both Koh Haa Two (Japanese Island) and Koh Haa Four.

Diving Koh Haa Two & Four begins in the lagoon shallows around 5 - 8m, gradually dropping off into deeper water on the outer (south) edges of the islands. The outside of Koh Haa Four extends to 45m + where the bottom becomes more muddy and less firm.

Diving Koh Haa Lagoon with Dive & Relax

The shallows of Japanese Island. especially inside The Lagoon, and facing west toward Koh Haa Four have created a wonderful hard and soft coral garden, and a great number of species can be found between 3 m and 10 m.

The diversity of species between the islands here is fantastic, with the sandy/rubble area between Koh Haa Four and Japanese Island providing countless subjects for the macro photographer.

The Resident Garden Eels

In addition to the macro life between Koh Haa Four and Japanese Island, there is a huge cement boat mooring block deeper, at 30m. Immediately beyond this mooring block is a huge field of garden eels.

If approached carefully, the eels will remain out of their burrows, waving in the water column to catch food and oxygen.

Garden Eels @ Koh Haa with Dive & Relax

As you would do with any deeper dive, please be aware of air consumption and no-stop dive times in the deeper areas of Koh Haa.

There are also two very old resident garden eels living on the shallower south side of Koh Haa Four. Say hello on your way past, but please try not to disturb them...

Diving Koh Haa Three into The Lagoon

Several excellent dives begin at the back of The Lagoon, on the west side of Koh Haa Three.

This side of Koh Haa Three has a long combination of sloping reef and wall continuing down to the sandy bottom around 15 - 20m which makes for an excellent dive. Over the sand and rubble areas there are coral bommies extending to 25 - 30m.

Divers can also head around Koh Haa Three into The Lagoon, either choosing to go south & west (left shoulder to the reef), or north & east (right shoulder to the reef). Both routes are quite different from each other and provide two completely different dives.

Diving Koh Haa with Dive & Relax

The south & west route is more shallow, with coral gardens, rocky ridges and a coral strewn sandy bottom leading into the lagoon. This dive has great macro life, including lots of lesser seen species over the sand and coral rubble close to the reef edge.

The north & east route is much more dramatic, with huge rocks and coral bommies leading to deeper water and home to millions of snapper, fusiliers, parrotfish, giant trevallies, great barracuda, emperors, and countless other species.

A finger reef stretches from the west of Koh Haa Three out toward Koh Haa Yai and Koh Daeng.

Snorkeling Koh Haa Lagoon

The shallow lagoon at Koh Haa is one of the best snorkeling sites in the Lanta Marine Park, home to thousands of healthy and robust corals, and hundreds of different marine life species.

This is also a fantastic place to see schools of bigeye barracuda, feeding parrotfish, wrasse, snapper, groupers, damselfishes, butterflyfishes, and sometimes hawksbill turtles and baby blacktip sharks in the shallows.

Snorkeling Koh Haa with Dive & Relax

There is a small sandy beach at the heart of the lagoon where you can swim ashore for a rest, however due to the shallow corals, we can't bring our boats to the beach.

In addition to the coral lagoon, snorkelers can also easily explore the shallow reef areas around islands two and four.

Just under the surface in The Lagoon, snorkelers can see crocodile needlefish, fusiliers, sergeant majors, and occasionally juvenile batfish from the school that lives on the outside of Koh Haa island Four.

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Koh Haa Lagoon Map - Dive & Relax

Koh Haa Lagoon Map

Koh Haa Lagoon
Visibility: 15m - 30m +
Level of Diving: All Levels
Snorkeling: Yes
Depth: 0m - 45m +
Journey Time: 25 - 35 mins

Check out our high season dive trips and PADI courses.

Diving Koh Haa Yai

As the largest of the Koh Haa islands, Koh Haa Yai is home to several very different dive sites and probably the largest amount of coral and marine life in this amazing archipelago.

The extensive coral coverage around this island provides several dive sites, dramatic underwater scenery, and extensive coral gardens, slopes and bommies.

Common Octopus at Koh Haa with Dive & Relax, Koh Lanta

We often see larger fish such as barracudas, golden and blue-fin trevally hunting schools of snapper and fusiliers along the reef. Malabar groupers are common, waiting patiently in the shadows, ready to ambush their unsuspecting prey.

Pufferfish, trumpetfish, wrasse, moray eels, soldierfish, groupers, cornetfish, surgeonfish, triggerfish, schools of snapper, nudibranchs, lionfish, and countless other species can be found around this island.

There are a great many interesting and seldom seen smaller and macro species found around Koh Haa Yai if you take a little time to look. Perfect for the underwater photographer.

Koh Haa Cathedral

There are three caves on the south west side of Koh Haa Yai, and approaching from the west, the first cave is smallish and only for the more comfortable/experienced diver.

The second cave is quite a bit larger, more like a cavern, and is connected to the third cave via a large 'window'.

Diving Koh Haa Cathedral with Dive & Relax, Koh Lanta

It is this third, cavernous cave which is famously known as 'The Cathedral' and is a 'must' for any suitably experienced diver when visiting the Koh Haa islands.

For those without any ear equalising problems, it's also possible to surface in The Cathedral where there is fresh air and some limited daylight shining through from the entrance. This is best done near the start of the first dive, before nitrogen has a chance to accumulate in your body.

Snorkeling Koh Haa Yai

There are two main snorkeling areas around Koh Haa Yai, a rocky and coral encrusted plateau near The Cathedral, and the stony beach facing The Lagoon.

Both snorkeling spots are home to many hard and soft corals, schools of tropical fish, and other marine life such as starfish, sea cucumbers, urchins, sponges, octopus, squid, cuttlefish, sea snakes, and occasional hawksbill turtles.

It's not uncommon for snorkelers to see schools of parrotfish or sea chubs swarming the reef shallows, munching on algae, or find themselves surrounded by damselfishes, fusiliers, or even a school of barracuda slightly further out in the blue.

Diving Koh Daeng

Koh Daeng (Red Island) is the smallest island to the north of Koh Haa Yai, and is attached to Koh Yai by a short coral/sandy ridge. Some people call this Koh Haa Six, but the traditional Sea Gypsy name is Koh Daeng.

What looks like a small island on the surface actually spreads out underwater into an extensive reef area with walls, slopes and coral gardens surrounding the island.

Diving Koh Haa with Dive & Relax

In the shallows of Koh Daeng we can really see the red colour of the rock on this island. The shallows are also the perfect place to see schools of moorish idols feeding on the algae which covers these rocks in the shallows.

The reef around Koh Daeng mostly drops to 25 - 30 m, however the connecting ridge to Koh Haa Yai is more in the 12 - 15m range, with gentle slopes on either side.

On the outer (north) side of Koh Daeng, the smallest of the Koh Haa Islands, we may occasionally see a whale shark cruising past in the blue.

Diving from Koh Daeng to the rocky Beach area on the east side of Koh Haa Yai is a very nice dive, and makes an excellent drift dive in a dropping tide.

Book online to save 10% on scuba diving trips and PADI courses.

Koh Haa Tides & Currents

When planning dives around the Koh Haa islands, is it worth remembering that a dropping tide will generally run north to south, and a rising tide will generally run south to north.

Some of the Koh Haa dive sites make excellent drift dives when currents are stronger around a full moon or a new moon.

Koh Haa Yai & Koh Daeng Map - Dive & Relax

Koh Haa Yai & Koh Daeng Map

Koh Haa Yai & Koh Daeng
Visibility: 15m - 30m +
Level of Diving: All Levels
Snorkeling: Yes
Depth: 0m - 35m +
Journey Time: 25 - 35 mins

Check out our high season dive trips and PADI courses.