For those yet to savour the delights of the Kingdom of Thailand, simply whispering the country’s name, conjures up a world swathed in a myriad of exotic beauty, mystical culture, mouthwatering food and breathtaking panorama.
The beauty of the country, which transcends from the lusciously green rolling mountainous terrain, to tropical jungles bursting with equatorial wildlife, will bring you to ancient Buddhist temples and sequestered monasteries, and the salt-scented air of idyllically pristine white sandy beaches. And all this without even unlocking the depths of the country’s vast archipelagos, and turquoise blue seas.
Undoubtedly, the jewel in the midst of Thailand’s exhilarating magnetism of a thousand distractions, is the moment you depart from the sultry, sensual, intoxicating topside world, and become reborn into an intensely unique underwater realm; the moment you become one with the magnificent seascapes which stretch before you, and some of the best dive sites the world has to offer.
Thailand offers superior diving all year round, and each region offers its own premier diving, at specified times of the year.
First, there is the Andaman Sea on the West Coast of Thailand, which offers exquisite diving off the tropical islands of Phuket, Koh Lanta, Koh Lipe and the Phi Phi islands, with Khao Lak and Krabi providing a mainland gateway to some of the most breathtaking dive sites.
Enjoy tropical climes and fantastic diving from November through to May on this coast of Thailand, as monsoonal winds usually hit from around June through October, with some dive sites becoming inaccessible. Day boats will however go out where weather permits, and this might be one of the best times to grab some of the best deals local dive centres have to offer.
In the Gulf of Thailand, the long stretching East Coast of the country, the tropical islands of Koh Samui, Koh Tao and Koh Phangan provide some of the most illustrious dive sites, with Pattaya and Koh Chang furnishing some fantastic wrecks, and other depths, to most definitely be explored.
In the Gulf of Thailand, divers flock to the flat seas and blissful weather from May to October, until the monsoonal winds arrive towards the end of September. Even then, there is still good diving and plenty of fun to be had in all these locations, no matter what the month.
After you’ve hung your fins up and put your 3mm out to dry, relax on the beach with a massage that’s easy on the pocket, sip fruity cocktails as the sun goes down, enjoy some authentic traditional Thai food, the laid back island style night life, and bargain at the wealth of local markets for some souvenirs of your time in paradise.
Elephant trekking, sunsets to die for and the unremitting nightlife of Bangkok are amongst Thailand’s other non-diving attractions not to be missed.
FAMOUS DIVE SITES: 
The Andaman Sea, North:
This is the place to come for mantas, whale sharks (from February to May), reef sharks and an overwhelming richness of marine life.
The Andaman Sea should be in the top 5 of every diver’s to-do list, and is best explored on a liveaboard, of which there are a plethora to choose from.
Richelieu Rock — Not just an infamous dive site in Thailand, this is a must-dive for divers across the globe. From February to May, whale sharks circle this site like satellites, and it is common to see manta rays, white tip reef sharks and whale sharks - all in the same dive. Be sure to equally absorb the vibrancy of the reef, and the diversity of the seascape and topography, whilst keeping a furtive eye open for one of the most sought after shark sightings. For Dive Shops in this area click here
Koh Bon/Koh Bon Pinnacle — If the elegant swoop of mantas haunt your dive dreams, ask for a dive (or three) at Koh Bon. You’ll also get the chance to spot leopard sharks and a very pleasing variety of eels. Other visitors to the reef include eagle rays, white and black tip reef sharks and swarming jacks, definitely not a dive to be missed. For Dive Shops in this area click here
Similan Islands:
- The Similan Islands became a Marine Park in 1982, and the waters around the nine islands burst with life. You will continue to find tuna, trevally and jacks, as well as being surrounded by a teeming diversity of macro marine life, and a seascape thickly coated with soft corals and giant sea fans.
- The eastern half of the Similans offers quiet coral gardens while the western side brings the challenge of bolder formations.
- The Similans are best accessed by liveaboard, and Khao Lak, which is on the West side of Phang Nga Bay, about 120km North of Phuket, provides the best access to the Similans. Day trips to the Park by the speedboat are also available from Khao Lak.
For Dive Shops in this area click here
Elephant Head Rock — The swirling currents here plump up soft coral forests, forming a wild swathe of vibrant colour. Sea fans grow to gargantuan proportions and there are heaps of swim-throughs. Leopard sharks, along with sea turtles and a mass of tropical fish, have made their home amongst the folds of these splendid reefs. For Dive Shops in this area click here
Andaman Sea, South:
Hin Daeng and Hin Muang — Boasting the Andaman Sea’s most elusive and unsurpassed pinnacle dives, Hin Daeng offers beautiful soft coral formations. Grey reef sharks have made both sites their home, sharing them with mantas and whale sharks, when in season. For Dive Shops in this area click here 
Phuket:
Many liveaboards begin their adventures here, and all the top Andaman dive sites are within easy access.
Phuket itself has a rich diversity of dive sites and tropical marine life to offer:
Koh Dok Mai – A superb wall and drift dive, with hidden caves and crevices lurking in its rock face. The beauty of this site becomes illuminated with the sun’s beam above, and is home to baby nurse sharks, and whale sharks out in the big blue, when in season. For Dive Shops in this area click here
Racha Noi and Racha Yai —Racha Noi has plenty to explore and experience, including mantas and whale sharks when in season, blue spotted lagoon rays, chevron barracuda and large schools of tuna and jacks. For Dive Shops in this area click here
Shark Point —This site ripples with scorpion fish, lionfish, lots of puffer fish, angelfish and a few resident leopard sharks. They all weave their lives among vibrant pink and purple soft corals. For Dive Shops in this area click here
Phi Phi Islands:
Stunningly enchanting, these islands are the inspiration for many an escapist film.
Bida Nai — After the swim-through packed with glass fish, you’ll find stealthy pipefish, legions of nudibranchs and several colours of seahorse. Voracious lionfish patrol the sea fans, while swirls of jacks circle overhead. Peek under branches of staghorn coral for napping leopard sharks, this is also a top spot for cuttlefish encounters.
Bida Nok — Breathtaking both above and below the water, this site crawls with sea snakes and hawksbill sea turtles. Moray eels, piles of wrasses and more leopard sharks keep the action humming, whilst soft corals, parrotfish, and giant clams remind you that mother nature's creativity knows no bounds.
Krabi, Koh Lanta Yai and Koh Lipe:
The South Western coastal town of Krabi hosts access to the enchanting Koh Lanta archipelago, and stunning Koh Lipe, which are both accessible by ferry. On the East side of Phang Nga bay, local marine life is both prolific and varied, as well as facilitating easy access to the Phi Phi islands, Hin Daeng, Hin Muang and Shark Point, (just in case you missed them).
Koh Haa – Translated to ‘5 islands’ in Thai, something for every diver to explore - swim-throughs, pinnacles, drop offs, caverns and chambers. Marine life varies from the elusive ghost pipefish, to abundant octopus, occasional hawksbill turtles and marble rays.
Koh Lipe – On the edge of Tarutao National Marine Park, comprising over 30 islands, countless reefs, and access to vibrant seas full of marine life. For Dive Shops in this area click here
The Gulf of Thailand:
If you’ve ever backpacked through Asia, the chances are you stopped (and perhaps even learnt to dive) on Koh Tao or Koh Samui. The chances also are, that you spent a few hazy nights on Koh Phangan for the Full Moon Party. Koh Phangan is also growing now, as a popular area for both learning to dive, and accessing some of the best dive sites the Gulf of Thailand has to offer.
Chumphon Pinnacle, Koh Tao —It’s always a good sign when schools of jacks are thick enough to hide an entire pinnacle, which is often the case at CP. If you’re looking for “Nemo,” you’ll find the entire extended family jittering around their host anemones. Whale sharks frequently show up from February to April, and the potato cod grow almost as big. Like many other sites in Thailand, leopard sharks also linger here. For Dive Shops in this area click here
Sail Rock, Koh Samui — What makes this site so great is that it sits alone on the seafloor, so that every animal looking for a home in the area, comes to Sail Rock. There’s a famous chimney swim-through that is usually packed with glassfish. Hungry aggregations of trevally jacks also stalk the clouds of smaller tropical fish. For Dive Shops in this area click here
Pattaya:
Pattaya claims an advantage over other parts of Thailand, as it is not usually subject to the monsoonal winds which grasp both the Gulf of Thailand, and the Andaman Sea. So diving is great all year round.
Wreck diving is definitely a highlight here, particularly the HTMS Khram and Petchaburi Bremen. Pattaya also offers easy access to other island dive sites.
Koh Chang - Close to the Cambodian border, home to the Koh Chang Marine National Park, and part of another beautiful archipelago in the Gulf of Thailand, Koh Chang offers some of the most beautiful and unspoilt diving in the Gulf, parading hard and soft coral gardens, a wealth of parrot fish, banner fish, groupers, barracuda and turtles. For Dive Shops in this area click here
Dive Summary: 
Depths: Can range from the surface to beyond 40 metres/140 feet.
Visibility:
- Gulf of Thailand: 10 metres/33 feet to 30 metres/99 feet, depending upon current and wind.
- Andaman Sea: 5 metres/16 feet to more than 50 metres/160 feet, depending on area, currents and time of year. Remember, whale sharks and mantas are most prevalent when there’s plankton in the water for them to feed upon, so don’t expect great visibility on those dives
Currents: From none to strong, depending upon site. Most exposed sites are washed by current, but that’s what brings in the big animals, so relax, enjoy the ride and prepare to brag when you get home. Bring your safety sausage.
Water Temperature: 31° C/87° F in summer and 26° C/78° F in winter.
Dive Season:
- Gulf of Thailand: May to October
- Andaman Sea: November to May
- Whale Shark Season: February to May.
Weather: There are two kinds of hot in Thailand: hot and dry, or hot and wet. But, the seasons actually vary quite substantially from the north to the south. Generally, the best time to visit for topside activities is the cooler season from November to February when temperatures range from 18° C/64° F to 32° C/89° F. This applies from about Bangkok south. In the north and at higher altitudes, overnight temperatures can dip as low as 8°C/46°F. In Thailand's summer from March to June, temperatures average 34°C/93°F to 40°C/103°F, with humidity in excess of 70 percent. April is the hottest month while July to October brings the most rain and 90 percent humidity.
Access: The country is well serviced by international airports, with most flights arriving via Bangkok. Once in Bangkok, small planes, trains, buses or boats will transfer you to your resort or liveaboard.
Skill Level: From novice to advanced. There are lots of opportunities for deep wall, current and cavern diving for advanced divers.
Scuba Gear: Most dive centers and resorts offer full equipment hire.
Length of stay: Plan for on a week on a liveaboard and a week topside as a minimum. If you can manage a third week, you won’t want for distractions.
Featured Creatures:
You can find whale sharks in season, mantas all year, leopard sharks, sea turtles, whitetip and blacktip sharks, eels, sweetlips, lionfish, eagle rays, giant schools of snapper, trevally, barracuda, clouds of tropical fish, heaps of anemone fish and soft corals
Language: Thai, with English widely spoken.
Currency: Baht (THB).
Tipping: Definitely tip your divemasters and liveaboard crew. Tipping is not mandatory at most hotel restaurants or upscale eateries since a 10 percent service charge is often added to the bill.
Transportation: Flights within the country are easy and frequent. Trains, boats and buses also go just about everywhere.
Major Airports:
- Suvarnabhumi Airport - Bangkok (BKK),
- Chiang Mai International Airport (CNX)
- Phuket International Airport (HKT)
- Pattaya (PYX)
- Udon Thani International Airport (UTH)
- Krabi
Religion: Mostly Buddhism.
Electricity: 220v/50Hz.
Airport Entry/Exit fees: A Tourist Visa is required for many nationalities and available at no cost and issued upon arrival. Check your country’s Foreign Office website or local Thai Embassy more information - check with your country of citizenship for exact requirements. The departure tax of approximately 700 Baht is included with the airfare.