The islands are indeed very beautiful, but untouched and undamaged they certainly are not. Environmental issues, particularly on Ko Samui where land speculation continues unabated as basic infrastructure issues like roads, water and waste management are left in the bottom of the drawer point towards the general unsustainability of the industry as it currently stands.
Home to an international airport and a number of ferry ports, Ko Samui has by far the flashiest accommodation of the three islands as it is increasingly catering towards jet setters happy to pay tens of thousands of baht a night, and while there are still many budget bungalows on Ko Samui, the overall rising price of land makes it increasingly unlikely that more will appear anytime soon.
Ko Pha Ngan, next in size and popularity, just to the north of Ko Samui, is home to the infamous full moon parties -- massive drug and alcohol fuelled all-night parties -- often attracting five to ten thousand people. Centred around what was once the most stunning beach on the island, Haad Rin, the beach now a Jekyll and Hyde affair, alternating between being a still rather pretty, though over-developed white sand beach; and a festering filthy armpit filled with ravers, drunken yobs, undercover police and some pretty slippery characters -- all depending on the phase of the moon -- we tend to steer clear of Haad Rin during the party! Parts of the rest of Ko Pha Ngan, particularly on the west and east coasts are still very good value -- pick and choose and you'll have a great time.