Diving in Thailand – guide from Divemaster

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With over 18 months spent in Thailand and more than 160 dives across various locations and conditions, we’re excited to share our subjective but heartfelt guide: Diving in Thailand.

Thailand boasts over 2,600 km of coastline, yet shore diving is surprisingly scarce. Most notable diving spots are accessed by boat, and the country’s dive sites can be broadly divided into two regions: the Andaman Sea and the Gulf of Thailand.

Diving in the Andaman Sea – Thailand

What you need to know about diving in the Andaman Sea in Thailand is that most dive sites are seasonal. This means that the best dives can be done from October to the end of May. Sometimes the season lasts longer, rarely shorter, although this isn’t entirely ruled out. There are two reasons for this. The first is the unfavorable sea conditions from June to the end of September. The second, hopefully, is the intent to preserve the reefs in their current state.

Koh Lanta – Best Diving Spots

I have to start with Koh Lanta when discussing the Andaman Sea. This is where I spent most of my “diving life” and where, in 2016, Karo and I had our first diving experience together. All dives from Koh Lanta are conducted from boats.

The main dive sites are Koh Haa, Koh Bida, and Koh Phi Phi, all within approximately 40 km of Lanta. You can reach them by large boat (1 hour and 45 minutes) or speedboat (40 minutes). There’s also a renowned site considered among Thailand’s top 3: Hin Daeng and Hin Muang, located about 80 km southwest of Lanta, with travel times of around 3 hours by boat or 1.5 hours by speedboat.

All dive sites near Lanta are located within national parks, meaning you can only dive with a professional dive guide in groups of up to four. Touching anything is prohibited, and you’ll need to pay an entry fee of 600 THB each time.

The average cost of diving from Koh Lanta is around 3,500 THB for two dives, usually including breakfast, lunch, beverages, guide service, and equipment. Occasionally, promotional prices offer three dives for the price of two. Koh Lanta has about 15 dive centers, giving you plenty of options in terms of boat size, comfort, guide quality, and even the food served.

Koh Haa, Koh Bida, or Koh Phi Phi?

A tough choice, as the first two spots offer entirely different experiences, landscapes, and marine life. Ideally, I’d suggest diving in both. For now, I’d skip diving at Phi Phi, but more on that later..

Diving at Koh Haa – The Five Islands

Koh Haa is one of my favorite dive spots. Within this archipelago of five islands, you’ll find over 10 different dive options. These range from the shallow Koh Haa Lagoon to the deeper Koh Haa 1, featuring a chimney-shaped tunnel starting at 5 m and ending at 17 m. Don’t miss Koh Haa Yai, known as “The Cathedral,” with its three caves resembling cathedral entrances

Diving at Koh Haa is suitable for everyone, even first-time divers. Visibility is usually around 20 m, there’s a variety of marine life, and with an experienced guide, you can avoid currents.

Diving at Koh Bida – Sharks and Seahorses

The Koh Bida islands (Nok and Nai) are known for their blacktip reef sharks, which hunt in the shallows around these islands. Importantly, these sharks are entirely uninterested in humans. On the way back from Koh Bida, you might also visit Hin Bida, an underwater rock often home to leopard sharks.

Wreck Diving from Koh Lanta – The Kled Kaew

Just off Koh Phi Phi lies a wreck sunk in 2014 by the Thai navy. This medium-sized (47 m) transport support vessel lies at 27 m, with the bridge at about 14 m. It’s a dive for experienced divers, and due to the depth, dives are often shorter. However, the Kled Kaew offers a unique experience with the abundance of fish surrounding it.

Diving from Phi Phi

Around Phi Phi, dive sites include locations along Phi Phi Leh’s western wall, such as Malong (nicknamed Turtle Rock) and Viking Bay. Viking Bay also features an artificial reef habitat that impresses many divers. However, dives from Phi Phi often come with crowds, which can detract from the experience.

Of course, you can visit both Koh Bida and Koh Phi Phi directly from Koh Phi Phi itself, but… well, aside from the lower cost, diving from the island often means dealing with crowds. I’ve had experiences where, out of nowhere, 40 divers suddenly appeared underwater. Additionally, the waters around Phi Phi are heavily trafficked with all kinds of boats. While diving, you’ll likely hear the sound of engines, and anyone who has dived before knows how distracting that can be.

Hin Daeng and Hin Muang – The Red and Purple Rocks in Thailand

As I’ve mentioned, these are the deepest dive sites in Thailand. At Hin Muang, the seabed reaches a depth of 80 meters, and strong currents are common. Hin Daeng is shallower, despite being only 200 meters away. Both sites are exclusively for advanced divers—not just in terms of certification (Advanced Open Water) but also the number of dives completed.

What both of these sites offer are truly breathtaking landscapes (the names of the locations speak for themselves). If you encounter a current, you’ll also have the chance to see larger fish hunting while smaller ones try to hide from the current on the reef. However, the ultimate highlight of this underwater experience is something else entirely: giant manta rays. Of course, you need a lot of luck to spot them. We were fortunate enough to see them a few times, and it was truly an out-of-this-world experience!

Similan Islands – Diving in Thailand from Khao Lak

Khao Lak is a medium-sized town, with its main feature being a large dual-carriageway road cutting through the center. The Similan Islands, along with the Surin Islands, are considered some of the best diving spots in Thailand, and certainly for snorkeling. Of course, this is a very subjective opinion and often depends on the conditions at the time.

One challenge with diving in the Similans and Surin Islands is that in most cases, you need to board a boat and spend a minimum of two days on it. Only one company offers day diving trips to Richelieu Rock.

RRichelieu Rock – The Crown Jewel

This was our primary goal in the Similans. Richelieu Rock is an underwater pinnacle whose name doesn’t actually come from Cardinal Richelieu, as commonly believed, but from a Thai Navy commander who shared the same name as the famous cardinal.

This site is suitable for all divers, although it’s advisable to have a certification allowing for dives deeper than 18 meters. Occasionally, strong currents and thermoclines can appear at Richelieu Rock, making the experience more challenging. However, the site generally offers excellent visibility, sometimes reaching up to 30 meters.

Here, the chances of encountering the largest fish in the world—a whale shark—are much higher than on Koh Lanta (though we weren’t lucky enough to see one).

Diving at Richelieu Rock is probably one of the most expensive in Thailand. Two dives with rented equipment and the national park entry fee cost 6,500 THB. This is because, at least in theory, park entries are limited.

Koh Lipe – zupełnie inKoh Lipe – A Completely Different Diving Experience in Thailand

Koh Lipe to mała wyspa położona na południu Tajlandii, w zasadzie zaraz przy granicy z Malezją. To jej położenie sprawia, że dKoh Lipe is a small island located in southern Thailand, near the Malaysian border. Its location makes getting there a less-than-comfortable experience. It’s not difficult, but it’s not particularly easy either. You can catch a speedboat from Krabi or Koh Lanta. If you don’t want to spend 3–4 hours on a boat crammed like sardines, you can opt for a shorter trip by traveling to Koh Lipe from Pakbara Pier and then taking a speedboat from there.

NaOur Top 3 Diving Spots on Koh Lipe

Koh Lipe offers completely different underwater landscapes compared to the sites described earlier. Due to its location and often moderate currents, the reefs around Koh Lipe resemble botanical gardens. It’s beautiful, colorful, not particularly deep, and close by. Most diving spots are just 15–20 minutes from the shore. For this reason, many dive shops on the island offer trips on longtail boats or speedboats. In both cases, you enter the water via a backward roll off the boat.

The proximity of the dive sites allows for up to four dives per day, with most operators bringing you back to the island after each dive.

Stonehenge – Koh Lipe

This spot is our absolute favorite dive site on Koh Lipe. It features stunning expanses of soft corals. The name “Stonehenge” comes from its resemblance to the famous Stonehenge with rocks scattered in a circular pattern. The site is breathtaking and suitable for all divers, though there can be strong currents. A skilled dive guide will help you navigate and avoid these currents. The maximum depth is 27 meters, but even at 10 meters, you’ll already enjoy the site’s beauty.

7 Rocks – A Surprising Dive Spot on Lipe

We had absolutely no expectations for this dive—it was our last one on Koh Lipe. Perhaps it was this lack of expectations, the general underwater tranquility, and a sense of relaxation that made 7 Rocks such a pleasant surprise.

The vast area is mostly covered with hard corals, but there are also patches of soft corals, including fan corals. This site is definitely for fans of smaller marine life. Highlights include large ghost pipefish (for their size), seahorses, and countless dancing shrimp.

8 Miles – Arguably One of Thailand’s Best Dive Sites

This title is somewhat ironic because, unfortunately, we didn’t have much luck here. We encountered really poor visibility, likely no more than 7 meters. Additionally, we faced strong currents, making our dive mostly about finding shelter from them.

Still, 8 Miles is undoubtedly worth visiting. It’s an underwater rock where, thanks to the strong currents, you’re likely to see relatively large fish—not only big species but also unusually large specimens of fish typically seen in smaller sizes. We were particularly amazed by the size of the batfish swimming in huge schools. It was an incredible sight!

Diving in Thailand – The Gulf of Thailand

If you open any guidebook, Koh Tao will be listed as one of the “top” diving destinations in Thailand. This small island in the Gulf of Thailand is the smallest of three closely situated islands—Koh Phangan and Koh Samui being the other two.

Unfortunately, Koh Tao’s dive sites do not compare to the spots mentioned earlier. Koh Tao gained its popularity in the mid-1990s, thanks to the extremely low prices of diving courses. To this day, it remains one of the cheapest places in the world to get certified.

Now, let me generalize a bit, though not without a grain of truth: the vast majority of freshly certified “Koh Tao divers” don’t actually know how to dive. The sheer volume of people and low prices have inevitably affected the quality of training. But focusing on the dive sites rather than the training quality, I must sadly admit that Koh Tao offers fewer and fewer rewarding experiences with each passing year. This is largely due to mass tourism and the lack of protection for dive sites.

It’s also worth mentioning that diving in the Gulf of Thailand can sometimes be impossible between November and mid-December (or even longer) due to stormy weather. Unlike the Andaman Sea, there are no seasonal closures of dive sites here.

Sail rock

Sail Rock is an underwater pinnacle that is also visible above the surface. Ironically, it is closer to Koh Phangan, which is where we dived from. However, we didn’t experience a “wow” factor at this site.

What stood out was the sheer number of fish. There are countless schools of various species, including larger fish. Both dives during our trip were conducted at this single site, which allowed us to fully appreciate the abundance of marine life present.

It’s also worth noting that during the peak diving season, this spot gets extremely crowded. There’s a high chance that, upon surfacing, you’ll see a “train” of boats lined up. If you were lucky enough to arrive early, like we were, your boat will be close to the dive site. Otherwise, you’ll face a journey through the waves.

Diving in Thailand – Summary

This rather extensive guide to diving in Thailand doesn’t exhaust the sheer variety of dive sites available. For example, you can dive from Phuket, with its highlight being the King Cruiser wreck. On the Gulf of Thailand side, you have the option to dive from Koh Chang. Diving is also possible from Pattaya, where dives on the Hardeep wreck come highly recommended.

I dare to say that wherever you find yourself in Thailand with access to the coastline, you’ll find a place to dive—sometimes better, sometimes worse. However, there will always be something exciting waiting for you underwater.

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