TODAY, THE WEATHER IS GOING IS GOING TO BE HOT. DAMNED HOT!
This was a magic line from the movie Good Morning, Vietnam, in which Robin Williams played the part of a US Forces radio disc jockey.
I was in Thailand, not Vietnam, but I couldnt help thinking of the movie as I struggled with my lightweight wetsuit in the humidity, sweat trickling through my eyebrows and stinging my eyes.
Dutch Frank, the onboard owner, always thinks positively. He is something of a gentle giant, and is inclined to come out with lines like this, but with the tag: How nice is that or Its nice to be nice!, supplemented by a broad contagious grin. His Thai crew, headed by Captain Jack, are programmed to grin in agreement.
One of the minority on board who actually bothered to struggle with a suit, and the only one with an underwater camera to worry about, I always seemed to be the last to leap down into the RIB from the main vessel. The other divers, in this case from Norway, Denmark and Germany, waited somewhat impatiently but were far too polite to say anything.
It was an unusually short liveaboard trip. We only had four days of diving, so I suppose every moment was precious; far too precious to spend sweating and waiting in the awkwardly bobbing boat while some underwater photographer got his act together.
The hard corals that formerly clad the massive granite boulders that make up the underwater topography of the Similan Islands had been blasted away in places by the Boxing Day Tsunami, but it is still worth diving.
There is plenty to see and, although the water is comfortably tepid in places, there remain tonnes of fish of all the Indo-Pacific species.
Similan means number 8 in Thai, and the individual islands are handily numbered rather than named.
It was good to get away from the holiday island of Phuket, with its sometimes oppressive hustle. Inevitably the proximity of the islands to such a centre of population means that plenty of other dive-boats will always be present. We were amused to see divers arriving the hard way, in primitive dragon-tail boats powered by all manner of different and equally smoky engines.
We aboard sy Siren managed to stay out of synch with divers from most other boats, so the dive sites we visited didnt get too crowded.
How did the sites vary Those familiar with Thailand will recognise the expression Same, same, but different.
I think in some ways this summed it up.
At first we would see the same smooth, round granite features. Often these underwater hills, polished smooth by years of wave action, reminded me of the upturned hulls of wrecked battleships.
Big round boulders piled up beside them where they disappeared into a sandy seabed. Gorgonia and other fan corals marked the points where currents speeded up to squeeze through confined places.
Where water was forced up and over slopes, great areas of pink soft corals flourished like a display at the Chelsea Flower Show. Banks of anemones gave the impression of bedding plants. Feather stars, often cadmium yellow, added to the bouquet.
Clouds of glassfish glittered in the sunlight. Black snapper clustered in groups in crevices between the boulders.
If my mention of currents makes the diving seem energetic, Id be misleading you. The current flows are very localised, and you need only to pick an alternative route in the lee of some convenient rock if you find the going too arduous. In many ways, I found the diving too easy!
The water was bath-like until a chilly upwelling from the deep ocean rolled in, bringing with it both shivers for most of my companion divers and water loaded with murky green plankton. Refraction, as different densities mixed, caused eyes to lose focus temporarily, and I was then glad of my 3mm full-length wetsuit.
Alas, it left many of my pictures a little less than sharply focused than I might have hoped.

WE ISLAND-HOPPED NORTHWARDS from the Similans, stopping off at Koh Bon and Koh Tachai on the way to Koh Surin. Always with one eye on a possible change in the weather, our final destination was the unprotected moorings at Richelieu Rock.
French for rich place, the name probably came from fishermen travelling from what was once French Indo-China. This isolated outpost has earned an enviable reputation among international divers for encounters with whale sharks, mantas and other pelagics.
These things dont arrive to order, and we could only spare two dives there, such was our short itinerary.
So apart from one large white manta that continually circled the rock, causing endless camera-toting divers to break into a sudden and pointless sprint, we had to content ourselves with observing the permanent residents.
When researching articles like this, I always try to concentrate on what makes the diving unique to one particular place, and by that I dont mean the divers wearing an assortment of odd clothing and looking like survivors of an air crash.
People got excited about seeing a seahorse or a ghost pipefish, but then they would, wouldnt they
Youd have to be pretty unemotional not to be turned on by the sight of a huge manta ray escorted by kobias gliding majestically over your head.
Its marvellous to watch a group of sweetlips gathered by a rock face in a pathetic attempt to look like one big fish.
Its wonderful to swim within a pulsating crowd, an enormous golden host, of yellow snapper doing a much better job of it.
Its always nice to encounter a hawksbill turtle. A couple in the Similans are in the habit of eating bananas offered to them from the boats.
You may object, but their shells look so glossy and perfect that they must be doing well on this diet.
Normally you see hawksbills eating sponges among the assorted corals of a tropical reef. Under water here, it made a change to see them surrounded by granite boulders that were covered in a thin layer of red sponges.
Different moray eels lurked, gulping the water in a threatening manner, with the brown spotted version ubiquitous.
Venomous scorpionfish are so common that one pays them little attention, but its a thrill to watch
a banded sea-snake, one of the most virulently poisonous creatures on the planet, hold its breath and calmly hunt in every nook for any tiny creature it can devour.
The one I photographed seemed oblivious to the wide-angle dome port pushed persistently in its face. I guess it knew nothing was going to try to eat it.
That said, it was the leopard shark that captured my imagination and, in the waters off Thailand, there seem to be plenty. Leopard sharks fulfil the role here of nurse sharks elsewhere in the world.
You find them lying lethargically on the seabed, pumping water through their gills and reluctant to move until you get really close.
Then, with a swish of their long tail and double dorsal fin, they turn and launch themselves into deeper water on their broad, wing-like pectoral fins, just as a nurse shark would do elsewhere.
The difference is that these sharks of the Far East look, well, so oriental!
Is it their golden colour and curiously mathematical design Instead of the smoothly contoured body of other sharks, they are ribbed in the style of a Chinese lantern. Is it those too-regular leopard-like spots Is it the almost rectangular spiracles or the eyes that are so un-sharklike
Once youve tired of looking at the leopard sharks, and with diving done for the day, back on board Siren you can enjoy a Thai-brewed Leopard beer with Frank. Its leopards all round!

SIREN IS ONE OF A RATHER SELECT GROUP of liveaboards, in that the owner is on board. Such boats have a unique atmosphere, and Frank van der Lindes is no exception.
Frank has always had a taste for adventure. He grew up on his familys boat in Amsterdam and became a truck driver, with trips to eastern Europe and further afield. He also travelled for fun, mainly in Africa, on his motorbike, sleeping under the stars.
Franks impressive physique yet friendly demeanour and huge sense of humour opens smiling doors for him wherever he goes. When he reached Thailand, he took up scuba-diving, and worked as an instructor. This quickly became less adventurous than he liked, so he bought a small motor-sailor, the Sampai Jumpa (See You Again) to start liveaboard diving trips from Phuket.
That wasnt enough either, so with his dad, a carpenter and boat-builder, he travelled to Indonesia to supervise the building of his next vessel, Sampai Jumpa Lagi (See You Again Soon), since renamed Siren.
The shipyard in Sulawesi was experienced in building wooden sailing boats for use as diving live-aboards. Komodo Dancer is one of them.
However, Frank had his own ideas, and the local builders had such respect for the hands-on skills of his dad that they willingly followed the duos instructions.
Siren is 34m long at the deck, with a broad 8.8m beam. She is massively built using ironwood, the only timber hard enough to resist the effects of wood-boring marine creatures. her style is that of a traditional phinisi gaff-rigged sailing yacht, but modernised to European standards.
Siren has 385sq m of sail, but when the wind is unsuitable or to meet the time constraints of a short itinerary, a 500hp Hino diesel engine comes into play. A bow-thruster makes it relatively straightforward to manoeuvre at sites.
There are three generators, and two water-makers that can produce 10 tonnes of liquid a day. So the en-suite facilities of the eight twin-bedded passenger cabins are well served, and there was always enough water for copious and refreshing showers.
Besides having individually controlled air-conditioning units and built-in safes, each cabin is equipped with its own computer, networked to a central server - so underwater photographers dont need to carry their own computer.
On underwater photography safaris a special table is fitted on the foredeck, so no one encounters problems with condensation when bringing camera gear up from air-conditioned areas into the extreme humidity normally encountered in the tropics.
Helping to avoid excess-baggage charges, Siren passengers are also supplied with all the dive gear they need. Nitrox 32 is free to those certified to use it, and good-value nitrox courses are available with any one of the three diving instructors/guides. Other toys on board include water skis.
The Thai crew of eight includes the captain, engineer, two chefs, two stewardesses and two deck crew, who also drive the pick-up boats.
Diving is conducted in small groups, though independent buddy pairs can make their own arrangements.
Frank is one guide, and, while I was there, Kiwi Brett Robertson and British expat Warren Murray looked after the guest divers in the water. Late-deployment SMBs are employed, and two RIBs are used as pick-up boats. One has a 200hp engine, so although it is usual to ride from Siren to the dive site, these rides are especially quick.
British divers will feel at home. The saloon is in the style of an English pub, with bar-stools and beams! There is also an excellent Italian coffee machine.
Included in the price of the trip are a range of Thai beers, Leo and Tiger among them. Meals are normally taken under the awning on the aft deck, and there is food to suit every taste.
Mine was a short trip, but normally they are of 10 days duration to the west coast of Thailand, the Similans, Surin, Koh Phi Phi and Dang Muang.
Frank and his partners are hungry young lions of the diving world, and the name of their company, Worldwide Dive & Sail, is no accident. An operation in Indonesian waters is next on their agenda.
As established diving liveaboard owners start to age, its guys like these who will step into the breach.

FACTFILE
GETTING THERE: John Bantin flew to Bangkok with Air Malaysia via Kuala Lumpur, and transferred from there to Phuket.
DIVING & ACCOMMODATION: sy Siren, www.worldwidediveandsail.com
WHEN TO GO: November through April is the diving season on Thailands west coast. Water temperature is 24-28°C, air temperature 27-34°C.
PRICES: A 10-day trip on Siren costs from £1365 through UK tour operator Geo-Dive, www.geo-dive.com, which will also arrange flights at prevailing prices. Less expensive trips are available on the smaller, less luxurious Sampai Jumpa.
FURTHER INFORMATION: 020 7499 7679, www.tourismthailand.org