During each day Nang Yuan island is besieged by many boatloads of day trippers who primarily come for the snorkeling . lots of the visitors cannot actually swim and are given large lifesaver vests, masks and snorkels before they plunge into the bay. There is certainly much to see in the water even very close to the resort, despite its shallowness and the thrashing about of the day trippers. It can be so beguiling, just floating around watching the sea life, that you begin to wonder (briefly) if there is any real need to do any proper diving! In the little bay we saw great shoals of the usual coral fish such as damselfish as well as several groups of parrotfish, a couple of cornetfish, loads of crabs, shrimp and goby duos and Jen even managed to spot a couple of small octopi but couldn't find me to tell me! The damselfish were particularly inquisitive and spent a lot of time deliberately swimming around us. This was very nice until we realised that they were taking the opportunity to nip us at the same time.

However, once we got going we really enjoyed the diving here. The organisation is small and they don’t get very many experienced divers . When we met our guide Pierre he was really chuffed, telling us, ‘Good, with your experience we can go straight away to Chumphon Pinnacle and dive deeper!’ In reality we didn’t and went instead to two other different dives; reflecting some of the disadvantages of less than rigorous organisation. Although we generally went to the sites that we were interested in, there often seemed to be lack of clarity about what was happening. At one stage another dive guide was arranging to go with us the following day and said that we could choose which site we wanted to visit. This was immediately stopped by the Thai clerical worker in the centre who called out ‘the dive leader chooses the site, not the customer’. The dive boat (a converted fishing boat) could certainly be improved (because the journeys are short they feel no need to update the facilities or speed of the boat,) but it was quite pleasant because, as the most experienced customers at the time (heaven forbid!) we and our guide were frequently the only divers on board . Most dives were relaxed and there was enough for us to see to ensure interest throughout.

The famed Chumphon Pinnacle, a group of rocks lying between 15 metres and 35 metres below the surface, was a particularly rewarding dive site that we actually visited twice. The rocks cover a distinct area and are a staging post for large numbers of fish including shoals of barracuda and batfish as well as some extremely large groupers and trigger fish. I have often been a bit dismissive of going down to 30 metres as it is generally darker and colder there with less to see.

But here was a revelation as great crowds of fish were swimming all around at the 28 metre mark, where there was a distinct thermocline (a meeting of warmer and cooler waters). At this stage Jen, in her 5mm semidry suit, was able to gloat and Pierre, in board shorts and vest, looked a mite chilly! There are often whale sharks here and we saw a free swimming remora fish (almost always found hanging around these much larger fish) but who he was with we never saw!

Elsewhere we found a wide range of environments including extensive anemone gardens, hard and soft corals in many different forms, as well as rocky outcrops and sandy bottoms . There's a wide range of critters out there including lots of sea cucumbers. These are, frankly, pretty ugly things that generally just lie around on the bottom looking a bit like poo. However, some here excelled themselves by actually moving, showing their moving bits and looking marginally more interesting. For the first time, Jen successfully spotted nudibranches without someone else pointing at them! These 'sea slugs' come in a huge range of colours and patterns although most we saw were the same variety.

Other less welcome visitors to the coral were the crown of thorns starfish. These are voracious eaters of the coral and our guide, Elly, suggested that a healthy reef can only tolerate a very small number for each hectare of reef but we saw at least four on a single dive site, definitely more than can be sustained over time.

On a number of dives we encountered a fair number of large titan triggerfish. Many of these were making large depressions in the sand or lording it over a particular spot on the rocks . This is behaviour linked to breeding and they can be quite territorial at that time. There were certainly a couple of times when we felt it better to go back out of their way as they were showing their displeasure (the trigger on their back rises and they start to swim straight at you!)

Koh Tao has become one of the leading places for people to learn to dive and this perfectly understandable when looking at the quality of the dive sites and the relatively low cost of training. So many outfits are competing that the price is being driven down all the time, with many dive shops on Koh Tao offering drastically discounted accommodation while you are being trained and long term discounts on diving after you are qualified.

NB we don't have any identification books with us so the captions for the pictures are a bit general (Simon please forgive us)! We're more than happy to hear of any mistakes or omissions to update the blog at a later stage.