Where are the best scuba diving spots in Thailand?

This question always depends on what you like when diving. Have you ever noticed how many places are in the "top 5 in the world"?! It's down to taste - do you like topography, big pelagics, little blennies, hard currents, or what? I have dived both sides and found them both great, but different. Koh tao is good for bigger (but fewer) fish and whale sharks at certain times of year.  Problem is that no-one on the island has anything to talk about except diving. Phi phi is good for wall (drift) diving and leopard sharks. Phuket is a bit rubbish. Similans are excellent if you like coral, smaller stuff and the occasional manta.  Richileu reef is an absolute dreamland - I have never seen anything like it. Personally, my favourite dive was at Hin Daeng/ Hin Muang, two dramatic, abundant pinnacles in the middle of nowhere. I was circled by no less than 4 manta rays and I will never forget it. Went there again afterwards and it was still good to just dive the reef. Make sure you check your seasons and pick the right place - it can be beautiful in west Thailand but rainy season on the east.

For training (price and convenience) then it is hard to beat Koh Tao. For quality diving, then the west coast offers more spectacular dive sites; especially those accessed via liveaboard boats.

The Surin and Similan islands are famous for scuba diving. I did Surin, water was beautiful, visibility was nuts. You can get there by boat from a couple places, I went from Phang-Nga province [different than Ko Pha-Ngan of full moon fame]. For learning everyone goes to Ko Tao. Never been myself.

Please take this with a grain of salt - as we operate in the Similan and Surin Islands. But the Similan and Surin Islands are very very good :) As are are Hin Daeng and Hin Muang (nearer to Phuket and Phi Phi). Koh Tao has a few spots that are good, but due to the sheer number of divers in such a small place, they can be crowded. It is also located in the Gulf of Thailand and the geology of the gulf is a huge shallow bowl. This means very little water movement - only 1 tidal change per day. Great news as it means less currents and warm water. Bad news as it means warm water - coral dies at certain temperature threshholds. It also means quite easy fishing...so not as many fish left :( As pointed out above - Koh Tao is a great place to learn to dive. Warm water, lack of currents and lots of other people there learning also. However, those seeking out recreational dives - it's not as exciting. Often overlooked is Koh Lipe. Another small island, but just going into a development phase. There are some sites nearby are good and a couple of very good ones further afield. The region we serve - Similan and Surin Islands are quite large. There are about 50 named dive sites and several more unnamed. Within this can be found 4 or 5 really, really god sites. Richelieu Rock is one of the ones listed in the "top 5" mentioned above :) It is Great - except when there are several boats there as the site is simply not large enough to support more than a few dozen divers. Also Koh Bon is spectacular for Manta Rays (the Pinnacle is particularly good). Koh Tachai is great for Sharks and macro. Elephant Head Rock is also a great spot for sharks and macro. For similan diving information http://wickeddiving.com

I had exact same questions a while ago. And as I was digging into this topic I’ve found plenty of information, various blogs and learning centers web sites.So I compiled it all into one guide to https://www.activityfan.com/archive/diving-in-thailand-amusement-park-for-beginners-and-paradise-for-professionals/?utm_source=Quora+Answers&utm_medium=Social&utm_campaign=Quora_Answers.Hope it comes in handy!

Thailand has a LOT of diving - some of the worlds best! There are a lot of online sites that can help here - the one I know best is DiveReport (am biased however) http://www.divereport.com/locations/south-east-asia/thailand/. There is the http://www.divesitedirectory.co.uk/ which can give more detail on actual dive sites opposed to locations.

I got my divining license on Koh Phi Phi and I thought it was amazing, very colourful and more variety of coral and fish life compared to where I went diving near Cairns in the Great Barrier Reef. Koh Tao was a bit disappointing because of the lack of visibility when I went but Chumphon Pinnacle was still teeming with fish life. I have heard that the Similan and Richelieu Rock are the best diving sites in Thailand with a chance of seeing the rare Whale Shark.

I have been to Phi Phi Island and I just got back from a liveaboard trip to the Similan Islands, in Thailand. Excellent diving, comfortable stay, and awesome food on board! Read my short blog post to see some amazing pics and get more information: http://www.plushplaza.com/blog/plush-places/plush-places-similan-islands-thailand/

Koh Tao is an excellent place for diving in Thailand and would be the place I would recommend for learning how to dive, It's where I did my open water through rescue diver and I lived there for two months while working on my divemaster. For the "Best" diving experience in Thailand the general consensus, amongst the instructors and divemasters, is a live aboard in the Similian's but that is only really an option if the focus is solely on diving. While Koh Tao won't necessarily impress a "seasoned" diver it certainly won't bore them and it is the definitive place in Thailand to learn. Specific school recommendations would depend on a number of things certifying agency desired (NAUI, PADI, SSI. etc.), the level of certification you want and the atmosphere you would like. Simple Life Divers ( http://www.simplelifedivers.com/) on Koh Tao had the right mix for me but it looks like there has been a lot of changes since I was there in 2005.