At the beginning of December I did a two day liveaboard from Koh Lanta around the Phi Phi Islands and out to Shark Point and Anemone Reef. The liveaboard is one of the boats we represent through AmazingLanta.com, and so I made a quick video tour and took lots of pix of the boat itself to give a better idea to future guests as to what it looks like.

Anyway, we arrived at Palong Bay, one of the Phi Phi dive sites, and my dive buddy Liam suggested we go in for a dusk dive on our own rather than waiting for a night dive proper. Liam had worked for a couple of seasons on Phi Phi and so knew the site well and was hoping we'd get to see blacktip sharks, as dusk is their feeding time.

We didn't have any luck with the sharks, but right at the end of the dive as we were about to start our safety stop, I saw three cuttlefish wrapping themselves around each other. I've never seen this behaviour from cuttlefish before, and the electric blue colour of their frills in the glare of my strobe was absolutely beautiful. (I have seen cuttlefish face stretching, but that's a different story). The cuttlefish were aware we were there, but unabashed by our presence - they barely backed away from us, so intent were they on mating. It was a truly great end to a dive and definitely makes me want to do more dusk dives.

That's free diving as in diving without scuba gear The Big Blue style, not getting scuba lessons for free! Freediving (also known as apnea) has been getting an increasing profile in the last few years with the world records set by the likes of Umberto Pelizzari and Tanya Streeter.

If you want to try freediving, there are beginners courses already been offered in the UK (see Free Diving - A Beginners Guide) - but it's probably a lot more fun to try out in sunny Thailand.

Blue Planet Divers on Koh Lanta, Thailand will be offering free diving courses from October. Here's what they say: "Blue Planet will offer Freediving (apnea) courses from the International organization AIDA recognized in over 40 countries. Blue Planet is the only dive center that will offer this type of diving activity in Thailand. Francois Gautier, Instructor trainer for the past 7 years and main organizer for all AIDA competitions, joins the team to teach all courses - from beginners to Instructor training. A great pleasure for us all !"

There's a full page of information about free diving and the free diving courses offered by Blue Planet Divers on their website.

I've scuba dived a couple of times with Blue Planet Divers and always enjoyed being on their boat - it was while diving with them that I had my near mystical experience seeing 5 manta rays and a whale shark in one dive - detailed in my piece about Scuba Diving on Koh Lanta. I'll be interested to hear how their freediving venture progresses.

It was a case of third time lucky. I'd been to Southern Thailand's twin pinnacles of Hin Daeng and Hin Daeng twice before, eager to see the manta rays that frequent the two dive sites. I'd heard plenty of stories from various divers about spectacular encounters with the legendary devil fish - "mantas in-yer-face" as one instructor enthusiastically put it. On both previous occasions, there'd been no sign of the manta rays. But this time, even as I sank only a couple of metres below the surface, my heart surged as I saw the unmistakable tip of a manta ray's wing flip over the top of Hin Daeng's pinnacle.

My buddy and I raced towards it, but we needn't have worried: while my previous encounters with mantas had been a few precious seconds spent watching them soar through the water and then spin away into the blue, here at Hin Daeng they were seemingly unphased by the arrival of divers. Over the next hour I hovered at around 15 metres, watching not one, not two, but five different mantas swirl around, above and below me, some veering by so close that they momentarily blocked out the light with their awesome, graceful bulk, their huge, smooth white underbellies bringing a different dazzle to my eyes. Frankly, I was having difficulty believing what I was seeing. Every moment I expected them to suddenly disappear, but they didn't. I couldn't stop grinning - this was a dive dream come true, the sort of dive you always hear about from other people that never seems to happen to you.

Already well aware of my good fortune as I did my safety stop, still watching the mantas circle Hin Daeng's apex, I idly glanced down and nearly spat out my regulator. There beneath us the creature every diver yearns to see, the biggest fish in the world - the whale shark. I grabbed my buddy, frantically signalling and pointing downwards, all decorum gone. We watched its distinctive blue and white-spotted, blunt nosed bulk move rapidly around the pinnacle and then disappear back into the deep. The surge of euphoria I first felt on seeing the mantas at the beginning of the dive had come back full tilt, leading me to clamber back onto the boat with a huge smile and offering condolences to those who had exited the water before the whale shark's brief appearance.

I'd come to see if Southern Thailand's dive sites had escaped the tsunami unscathed, and this dive was the most emphatic positive answer imaginable. On my previous pre-tsunami dives I'd had to content myself with the twin peaks' more reliable inhabitants, including clusters of basking leopard sharks, groupers and cuttlefish, all set amongst the dramatic backdrop of Hin Daeng's sheer drops into the ocean's depths. Strong currents and murky viz mean that this isn't a site for novice divers without an experienced guide: Both peaks have a diverse collection of coral and critturs clinging to them as a vantage point in the middle of the sea. Even without the mantas, the two peaks offer a memorable dive location - with them, it makes for truly unforgettable diving.

Hin Daeng and Hin Muang are just one of the top notch Southern Thailand dive sites that are scattered to the east of Phuket. There's also the towering limestone rock of Koh Bida Nok and the circle of craggy islands known as Koh Haa. The sites are most easily accessible by day trips from the Thai islands of Koh Lanta and Koh Phi Phi, or by liveaboard from Phuket. Koh Phi Phi, world famous as the filming location of the movie The Beach, was badly damaged during the tsunami but has made a rapid recovery in the ensuing months with hotels and dive operators already re-opening. The laid back island of Koh Lanta, by comparison, was almost left untouched, and during my visit there were numerous dive shops offering day trips to the three key sites.

Thanks to their relative remoteness, these sites have all remained in great condition, untouched by the tsunami or the impact of tourism. Indeed, Koh Haa's circle of five huge oceanic rocks looks like the secret lair of a James Bond villain. The rocks form a breathtaking lagoon that is protected from the outside elements. Underwater, Koh Haa is as unabashedly pretty as it is on the surface. Koh Haa One is a fascinating wall dive, with serried rows of coral resembling aquatic rice terraces. There's a swimthrough known as The Canyon, at the deepest part of which live a tigertail seahorse, bright yellow and happy to pose for photographs. There's also a coral chimney which opens out into an easily exited cave at 7 metres. What I found overwhelming about dives at Koh Haa was both the sense of space - visibility was uniformly excellent on each of my visits - and the sense of abundance. There are so many fish around, and with a good dive guide, there are numerous hidden treats to be discovered, like the Durban hinge beak shrimp and ghost pipefish.

Koh Haa Yai is possibly even more dramatic thanks to The Cave, an airpocket where you can ascend and be inside the rock itself amongst the stalactites and stalactmites. The shaping of the rock by centuries of erosion makes it feel almost cathedral-like once inside, and the play of light on the water as you ascend and descend is quite unique - and can also be a little disorientating, so care is required. The dive site proper is a big wall with a shallow reef at its top, amongst which we found two octopi mating and a lone barracuda toying with a huge fishball just off in the blue.

The lagoon itself also offers some great shallow diving, with a pristine reef that harbours mantis shrimp who eye passing divers suspiciously and, after a lot of peering in crevices, the harlequin shrimp, universally known to dive guides as "the funky shrimp" as its amazing colours make it look like it's ready for a night at the local disco. It's the stuff of a macro photographer's dreams.

Koh Bida Nok is also primarily a macro paradise: it's a huge rock that forms a near vertical craggy wall in the water, down to around 30 metres, that stretches around into a shallow reef. There is a profusion of corals here, along with plenty of creatures making their homes in the wall's crevices. Whale sharks have occasionally been spotted here too, but it's the small stuff that generally provides the interest. Strong currents and poor visibility on each of my visits mean that, in truth, I can't say this site was a personal favourite, but that was more bad luck on my part than anything else.

Given the variety of dive experiences on offer from these three sites, it's worth taking time to explore each of them in turn. They are dive locations that repay revisits, each one with its own unique character that lingers long in the memory. Certainly the manta rays of Hin Daeng and Hin Muang are a headline attraction, but their appearance isn't essential for great diving experiences amongst these underwater gems in Southern Thailand.

[This article first appeared in Asian Diver magazine]