THE Thai island of Koh Samui used to be the exclusive preserve of mostly-European back-packers. They would pay a few dollars a night for accommodation, spend the same amount on mind-altering substances and wonder why life couldn't be this idyllically hazyevery day in Munich, Melbourne, Milan and Manchester. In those halcyon days, the beaches were virtually free of people and flanked by only isolated pockets of accommodation, usually in the shape of straw huts built by the few entrepreneurially-minded islanders. Most Samui people continued to pick coconuts for a living. Then, in the mid 1980s, came progress, in the form of Lonely Planet-style guides and an airport. Developers zeroed in with a vengeance and the main beach, Chaweng, was changed in the space of a few years from a ramshackle collection of huts to a series of resort-style bungalows. Other hotel chains took over whole east-coast beaches to ensure exclusivity; the Dusit and Allson Euphoria will shortly be joined by a Mandarin Oriental resort. For all the whirlwind change here, there and everywhere, Samui has a way to go down the degeneration path before it has the sex-and-cess-pit atmosphere of Pattaya and parts of Phuket. At Chaweng, the girlie-bar and disco proliferation has been kept a distance away for reasons of nature: a large swamp, perhaps appropriately, separates the beach-side accommodations from the night-life district. It's easy to play isolationist during the day, along Chaweng's splendid four-kilometre length, and act the party animal at night. There are plenty of options when pursuing the latter course of action, including the Reggae Pub, which stands as a kind of yuppified shrine to the hippy discoverers of Koh Samui. It is built in the traditional Thai style, in memory of reggae star Bob Marley, a Jamaican musician whose vast daily consumption of illegal substances was legendary. Busts of Marley abound, and an imported DJ from the Caribbean plays non-stop reggae at bomb-blast noise level. Any similarity to the old backpackers' haunts is purely coincidental. The Reggae Pub has a fine dining room, swish waiter service, up-market prices and a clientele who dress in Ralph Lauren after-the-beach evening wear. During the day, Samui's beaches are fairly lifeless places, with only the odd aquatic yobbo on a jet-ski to disturb the peace. Less than an hour away by boat, the charming cloak of tranquillity descends on Ang Thong national park, one of Thailand's true marvels. In their infinite wisdom, Thai authorities forbade developers from getting their greedy fingers on even one square metre, which must be a source of anguish in some boardrooms. The park has islands galore with white-heat beaches and see-to-the bottom ocean. The message to tourists and locals alike is look - but don't touch: this is what Samui, Phuket and Pattaya were like before the Modern World came along. Day-trippers are allowed on to the islands, with the proviso that they keep to footpaths and adhere strictly to the no-litter rule; a half-hour hike to the summit of the main island gives a stupendous view across the chain. On the distant horizon are the inhabited islands of Koh Phangan and Koh Tao, said to be reminiscent of Samui a decade or more ago, where Robinson Crusoe huts - mosquitoes no extra charge - can be had for US$5 a night. In contrast, the top-end accommodation on Samui starts at a top-end price of more than US$300 a night, at the gloriously landscaped Santaburi Dusit, down to US$10 for huts on the less-popular beaches. Now is the time to negotiate a good deal, either through a travel agent or bargaining in the hotel lobby. Frantic building has produced a glut of rooms: at last count there were some 7,000, about half of international standard. The situation at Samui is likely to change a lot more. There is talk of increasing the frequency of flights and expanding the runway so bigger, jet-engined planes can land.