Limited access for foreigners kept this emerald isle under the radar but restrictions have now been removed. Part of an archipelago of pristine islands in the Gulf of Thailand, this lush tropical Eden is a great base for island-hopping, while its tiny size (nine square kilometres) makes it easy to explore on motorbike or scooter. Most beaches are pebbly but Bai Cay Men comes straight out of a postcard, with white sand lapped by an azure sea – and you can even camp here. Whales are worshipped as ocean deities on the island, so check out the whale skeleton at Dinh Nam Hai Ngu Than temple. Accommodation is mostly of the budget persuasion and fills up on the weekends, so try to come mid-week.

Ever wondered what Thai beaches were like 20 years ago? You’ll find the answer here. Bobbing in the Gulf of Thailand, the crescent-shaped island is about 25 kilometres west of Sihanoukville and accessed via a 45-minute ferry (speedferrycambodia.com). Once the site of a Khmer Rouge military base, the island has shed its dark past and, today, it’s all sun-kissed sand, turquoise water and a chilled vibe. No two days are alike: cycle through the jungle, bathe under waterfalls, seek out the bioluminescent plankton after dark – or just glue yourself to the beach. Most travellers plop down on the eastern Saracen Bay, thanks to its proximity to the main pier. Venture west to Lazy Beach or Sunset Beach for a more remote day out – not to mention sorbet sunsets. Cars, Wi-Fi and ATMs are foreign concepts here, so set your out-of-office reply and explore the island before everyone else catches on.

In spite of Bali’s unwavering popularity, this island – just a 30-minute boat ride away – has remained untouched; a place of raw and rugged beauty with soaring limestone cliffs dipping to gorgeous coves with evocative names like Crystal Bay. Penida was traditionally a place of exile, both for convicts and the mythological demon king Mecaling and its haunted reputation kept tourism at bay. But change is in the air and rugged adventures await those looking for something wilder than a debauched night in a Bali nightclub. Ghosts aside, Penida is not for the unfit or faint-hearted. Getting into Goa Giri Putri temple means crawling through a cave, while travelling anywhere else involves treacherous roads and traversing steep cliffs via hundreds of steps. The rewards? Exquisite scenery, fabulous snorkelling and the chance to swim with manta rays.

White, unspoiled beaches. Tick. Lush palm trees and jungle. Tick. No crowds. Tick. Koh Mak in the east of the country is the embodiment of all your Cast Away fantasies. Accessed by boat from Laem Ngop or (in season) Koh Chang, Koh Wai and Koh Kood, Koh Mak remains one of the least-developed Thai destinations and its quiet, laidback charms contrast vividly with the party-hard vibe of big cousin Phuket. Instead, the infinitely more low-key activities here range from cycling on one of the relatively new tracks around the island, snorkelling in the national marine park or simply blissing out with a book in a hammock strung up between one of the 10,000 or so palm trees. Accommodation-wise, digs on this island are mostly small so it’s best to book for high season (November through March) before catching the ferry.

Described as South Korea’s Jurassic Park, this mystical island measures just 72 square kilometres but soars to a height of almost 1000 metres and boasts glorious forests and jutting shores. Although it isn’t a secret to nature-loving South Koreans drawn to its sacred spirit, the island’s far-flung location in the East Sea has kept it pristine and concessions to foreign tourism are few. Forget lolling around in a bikini, it’s not that kind of place. Instead book a hotel or homestay, get your hiking boots on and hit the spectacular Haengnam Coastal Walking Path, which clings to the cliffs. For stunning bird’s-eye views, climb the volcanic peak of Seonginbong (five hours return) or take a more leisurely cable car ride to Dokdo Island Observatory. A boat tour around the island is also sure to leave you spellbound.