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Dive Koh Haa Yai

Mu Ko Lanta National Park

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 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.

Day Octopus (Octopus cyanea) @ Koh Haa

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'.

Cathedral @ Koh Haa with Dive & Relax

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.

Koh Haa Yai is usually dived along with Koh Haa One or Koh Haa Lagoon.

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 dive trips and scuba courses on Koh Lanta.

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.

Find out more from the Thailand Department of National Parks on the Mu Koh Lanta Marine National Park.

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

Koh Lanta Dive Sites

Find out more at the Thai Department of National Parks.


Certified Diver Prices Online Price Walk-In Price
Koh Haa / Koh Rok(all levels of diving) ฿3,150 ฿3,500
Koh Bida / Koh Phi Phi(all levels of diving) ฿3,150 ฿3,500
Hin Daeng & Hin Muang(experienced divers only) ฿3,950 ฿4,300
Shark Point & Anemone Reef(experienced divers only) ฿3,950 ฿4,300
  • Minimum Open Water Diver, or equivalent.
  • All trips are 2-tank dives. Includes free equipment rental, lunch & soft drinks on the boat.
  • Scuba Skills Refresher for extra ฿900 when Booked Online (Normal Price ฿1,000)
  • Does not include Marine Park Diving Fee: Adult ฿600, Child: ฿400 per day.

Our Boat Trip Schedule

Our dive trips depart Koh Lanta in the morning every day from the south end of Long Beach, returning to Koh Lanta around 1:30 - 2pm, depending on how the day goes.

Week Day Boat 1 Boat 2
Monday Koh Rok Islands Koh Rok Islands
Tuesday Koh Haa Islands Hin Daeng & Hin Muang
Wednesday Koh Bida / Phi Phi Koh Bida / Phi Phi
Thursday Koh Haa Islands Koh Haa Islands
Friday Koh Haa Islands Hin Daeng & Hin Muang
Saturday Koh Bida / Phi Phi Koh Bida / Phi Phi
Sunday Koh Haa Islands Koh Haa Islands
  • All trips are 2 dives a day
  • Trips depart from the beach at our dive shop @ Lanta Castaway Beach Resort
  • Trips Depart 8/9am, return 2pm
  • Dive & Relax is open from Oct 15 - May 15.
  • E-mail us info@diveandrelax.com in advance with any questions, or to make a booking.

We may schedule a Shark Point & Anemone Reef dive trip or a KledKaeo Wreck dive trip upon request. A minimum of 5 divers are required for these trips, please let us know if you are interested.

We love to dive as much as possible during the high season, however all our dive trips depend on the weather, sea conditions, currents and minimum numbers and may be subject to change at short notice.

Book online to save 10% on dive trips and scuba courses on Koh Lanta.

For more information on our weather and climate, check out the best time to visit Koh Lanta.

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Diving, Snorkeling & PADI Courses

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  • Please let us know:

    • when will you arrive on Koh Lanta?
    • your previous dive experience?
    • which diving activities you are interesed in?
  • If you're already here on Lanta, you can call or WhatsApp +66 (0)89 050 3009