It's not widely known that Lantau Island has a doppelganger. In the southern Thai province of Krabi lies a similar-sized island that also has long sandy beaches, a mountainous spine and an 'away from it all' feel. The sense of deja vu in this corner of the Andaman archipelago extends to a fishing village on stilts, herds of buffalo and hidden waterfalls - although here you need an elephant to reach them. The islands even share the same name. Well, almost. Unlike its Hong Kong twin, Koh Lanta - 'Lanta Island' - lacks an airport, so to get here, it's best to fly to Phuket and hop on the twice-daily ferry that zips across the electric blue ocean. There is a brief stop en route, at Phi Phi Island, where limestone rock formations, translucent water and squeaky white sand tempt awestruck passengers to jump ship. Phi Phi's beauty comes at a price, however. Hordes of day trippers compete for postage stamp-sized patches of sand and rows of bungalows are squeezed in, cheek by jowl. Stay in your ferry seat, stick your nose in a guidebook and refuse to be led astray. The next time you look up, the green mountains of Koh Lanta will be looming. Despite playing perennial bridesmaid to Phi Phi, Koh Lanta has long seduced its share of suitors. The sand may not be as talcum-powder soft and the sea is a shade less turquoise, but being positioned in a rainforest-cloaked, island-studded national park and having a laid-back beach scene and lower prices do much to compensate. The commotion that greets an incoming ferry is as close to rush hour as it gets on Koh Lanta. Suitcase-toting tourists are ushered into air-conditioned vans and whisked away to nearby resorts. Budget-conscious backpackers haggle with tuk-tuk drivers as if their lives depend on a few saved baht and pushchair-packing parents negotiate with hotel touts who won't take no for an answer. Having made it this far, many arrivals venture no further than the first beach they come to. Khlong Dao is the busiest on the island, yet, if the three-kilometre bay were on Phuket, it would be described as 'undiscovered'. A few dozen sun-blistered northern Europeans bake on the sand - Koh Lanta's version of a red tide. The best way to explore the island is by moped - if you dare. The girl at the rental shop is happy to accept a Hong Kong library card as a deposit and advises against wearing a helmet. ('No need; your head will get hot.') She's doubtful about the merits of insurance, too, but as I prepare to set off, she warns me to move to a hotel on higher ground. Koh Lanta suffered 11 fatalities in the 2004 tsunami and locals are understandably edgy after recent events in Japan. But this intense fear of another giant wave contrasts sharply with an indifferent attitude to road safety. There were more than 250 traffic-related deaths nationwide during the Thai New Year celebrations this year, but, at the rental shop, no one bothers to ask whether I have a driving licence. It's a scenic 40-minute ride from Khlong Dao to Lanta Old Town, which is a dead ringer for Tai O. The pungent smells, Buddhist temples and seafood restaurants are reminiscent of Lantau's equally remote fishing village. Here, too, houses are built on stilts and there's a strong community spirit borne of isolation and centuries of self-reliance. While parts of southern Thailand wrestle with political and religious tension, Lanta Old Town is a model of social harmony. The original chao leh (sea gypsies) co-exist with the indigenous Muslim population and Thai-Chinese merchants whose ancestors arrived when the port was a trading stopover for vessels sailing between Phuket, Penang and Singapore. With those halcyon days long gone, the easy-going settlement is seeking new streams of income. A few of the old teak shophouses cater to sunburned sightseers by offering boat trips to nearby islands, but tourism here is still in its infancy. In Lanta Old Town, it's easier to buy engine oil than tanning oil. For now. In common with its near-namesake in Hong Kong, property prices on Koh Lanta are spiking. Developers intent on creating the next Phuket are racing to snap up pristine parcels of coastline. Estate agents are multiplying and roadside hoardings lure farangs (foreigners) with artists' impressions of luxurious beachfront villas. Owners of the last few rickety bamboo huts seem unwilling to go without a fight (or a substantial payoff) but are increasingly hemmed in by chic boutique hotels and upmarket resorts. Ramshackle reggae bars still thump out hypnotic bass lines but they, too, appear to be living on borrowed time. The far south of Koh Lanta is the exception, having seen relatively little high-end tourism investment. And for good reason. A few kilometres before the main road reaches the most sublime stretch of shoreline on the island, it degenerates into a dusty potholed track. There are rumours that work to complete the road will begin in the summer. 'They say that every year,' Pop says, shaking his head. The long-suffering proprietor of Baan Phu Lae, a low-key resort on unspoiled Bamboo Beach, is not having a good year. The economic downturn in Europe was already affecting bookings when heavy March rains flooded large parts of southern Thailand. Images of stranded tourists being airlifted from holiday islands made international news and although Koh Lanta got off lightly, reservations dried up faster than the sodden ground around his bungalows. Pop frowns when I suggest that the new road will bring him a steady supply of guests. 'My dream was to run a small beach resort and wake up to this view every morning,' he explains, gesturing towards the deserted beach, azure sea and mountains. 'We don't want tour buses and jet skis here.' Pop may not be waking up in paradise for much longer. He's not originally from Koh Lanta and is at the mercy of a local landlord who is about to raise his rent. The hotelier faces a dilemma: 'It's getting expensive here, but I don't know where else to go.' Residents of Hong Kong's largest island know how he feels.