Today it's one of Thailand's premier diving locations, but Koh Tao, or Turtle Island, has in the past been a pirate's hideout, a layover for fishermen, a prison and a badly-kept backpacker secret. While some say the island took its name thanks to its turtle-like shape, other say it took its name from the turtles that used to breed plentifully in its waters. Today the turtles largely go elsewhere to be replaced by the thousands of recreational divers and other tourists who flock here annually. The island is ranked number two worldwide for the issuing of PADI certificates. (Top spot is held by Cairns, Australia.)

Koh Tao also has plenty to offer non-divers, with an array of non-water based activities such as hiking to yoga on offer. Those willing to escape from the congested diver hotspots are rewarded with gorgeous beaches, great viewpoints and hospitable locals. Of course if you are diving, Koh Tao is a must, with some of the best diving in the Gulf of Thailand.

Western travellers first stumbled on Koh Tao in the 1980s, leading to the first rickety bamboo bungalows being thrown up. Within a decade, the island became a well-established alternative to Ko Pha Ngan and Ko Samui, thanks to its fine snorkelling and the cheap huts. In more recent years, Koh Tao has exploded, with more than 100 resorts open by 2001 and the number of diving schools sprouting along with them on the 21 square kilometre island. The rapid development has been accompanied by unregulated construction, which has transformed Mae Haad and Sai Ree from traditional wooden villages with dirt roads into carbon copies of the main centres on Pha Ngan, Samui and Phuket. Of the resorts from the early days, only Rocky Resort on Ao Thian Ok and Char on Haad Sai Nual remain.

The busiest time of year is Christmas-New Year, when it can be difficult to find a bed, but through the rest of the year it's never too crowded. The ongoing violence in Thailand's deep south, the murder of a young Welsh woman on nearby Koh Samui in Christmas 2005 and the coup of 2006 have all contributed to a drop off in numbers, but none of these issues, have much to do with Koh Tao. The island is generally very safe and with its great variety of activities and places to stay, there's never been a better time to visit.