The 80 islands off the Thai Gulf coast of Surat Thai province, 650 kilometres (403 miles) south of Bangkok, have a different character to those in the slightly more crystal Andaman Sea. A - mellow charm pervades its main three inhabited Islands: Ko Samui, with its mix of unhurried sun-worshippers, partying types and New Age vibes; the rugged hedonistic backpacker frontier of Ko Pha-ngan with its full moon parties; and the remote divers' domain of Ko Tao.
With smart hotels, gourmet restaurants, luxury spas, second homes and the continual presence of New Age pilgrims, Samui is more cosmopolitan than Phuket, yet it hasn't forgotten its roots. While the jet set could dispose of $500 a night in a palatial villa on on a virtually private beach, backpackers - who pioneered travel here in the 1970s and '80s - can still find beach huts for under B300. The local infrastructure reflects this demographic; from a Tesco Lotus hypermarket and a British pie maker to plans for an airport in the south to receive national carrier Thai Airways. Yet from the lush forests of the mountainous interior to its rugged capes and sweeping beaches, Samui's primordial beauty remains its greatest asset.
The area of Nathon around the ferry port is Samui's commerical and official hub, with many Hainan-influenced teak shophouses, a bustling market and a diversity of delicious hawker food. Heading north at Ban Bang Makham is the main stadium for buffalo fighting (Samui s indigenous sport), where events - advertised on trucks - take place at 5.30pm, usually during festivals.
The sea along the North Coast is a little murkier than in the east, but it remains calm throughout the year. The good-value, wellspaced accommodation along this coast appeals to backpackers and long-termers. An attractive fishing community compensates for Had Maenam's less appealing beach, while
Had Bophut is easily Samui's most charming village - quaint old shophouses overlook its beach, many converted into guesthouses, restaurants and shops. Further east and home to the 12-metre-high (39-foot) landmark statue in Wat Phra Yai, Bangrak) has the edge over the rest for eating, drinking and watersports. There's not much nightlife in the north outside Bophut, though on full moon night the coast reverberates with the s o und of revellers being feried to and from Ko Pha-ngan (see p237 Moon dance).
Hugging a picturesque crescent of fine sand, swimmable waters and arching palms, Chaweng is either party central or a vaguely sleazy lesson in over-development to be avoided. Both views are valid, but in among all the dross and congestion, you'll find some fine restaurants and funky bars. There's even secluded beachside accommodation - you just have to look hard to find it. Chaweng is also home to Samui's main Thai boxing stadium (Lagoon Road, 9pm-lam Mon & Fri, B500).
Over a ridge with giddying northwards views (near Beverly Hills Cafe), yawns Ao Lamai. Coral-strewn and shallow in the north (with independent resorts), the bay's southern end is stunning, with crystal waters and sand-studded granite boulders, including Hin Tin and Hin Yai. Just one kilometre south on Thanon 4169 (the island's ring road), these headland rocks resemble male and female genitalia, spawning crowds and souvenir stalls. Mid-bay, Lamai town is a mess and perhaps best viewed from the precipitous Overlap Stone (3 kilometres/ two miles south on 4169). The centre is dominated by prostitute-filled bars (much more so than Chaweng) and mediocre restaurants.
While the south's barely disturbed beaches - especially around Lipa Noi and Laem Set - are as good as the far busier northern ones, you can also head down Thanon 4170 for surprising vistas of rolling fields, terraced rice paddies, water buffalo and intriguing Wat Khunaram (Thanon 4169, east of Hua Thanon) - where fans of esoterica might be interested to see the displayed body of marathon-meditating monk Luang Pho Dang. Uncle Nim's Waterfall & Magic Garden, an extraordinary sculpture park based on Buddhist scriptures, is also worth a look. At Ban Saket, turn inland off 4169 on to an asphalt road, then hang a right a kilometre before the end (ask for Nam Tok Ta Nim). The mountain views are equally impressive.

ACTIVITIES
Samui's fine diving and snorkelling reefs (best from May to October), suffered coral bleaching in the 1997 El Ninio.
They're Recovering well, but generally speaking the further offshore the reef, the more likely it is to be teeming with life. Sites include Sail Rock's famous natural chimney, and Chumphon Pinnacles' whale shark habitat. Easy Divers (0 77413373) and Samui International Dive School (0 7742 2386) both have branches all over the island. For low-volume advantages, try the Dive Shop (Beach Road, Chaweng, 0 7723 0232) or Discovery Dive (Amari Palm Reef Resort, Chaweng, 0 7741 3196). Other watersports, from windsurfing and parasailing to the selfish indulgences of jet-skis and 'banana floats', are most prevalent at Bangrak and Chaweng.
'Ride with photo ops' would be a more accurate term than 'elephant trekking' for numerous tours, though it's a leisurely if jerky way to explore the interior. Living Thailand (Ban Nok Sai, 0 77418680/1) and Island Safari (Chaweng, 0 7723 0567) are both professional (from B300 for 15 minutes). Meanwhile, foodies can learn Thai cooking at SITCA (Chaweng, opposite Central, 0 7741 3172/www.sitca.net) for 13895.