Simon N. Ostheimer, for CNN • Updated 1st December 2015
Editor's Note — CNN Travel's series often carries sponsorship originating from the countries and regions we profile. However, CNN retains full editorial control over all of its reports. Read the policy
Thailand (CNN) — Unlike the isles just over the horizon, including Lanta, Phi Phi and Phuket, the islands of Trang, a sleepy province in southeast Thailand, remain remarkably under the radar.
Yet they're just as magical as their more famous contemporaries, with crystal-clear waters and inspiring scenery.
They're also one of the kingdom's last refuges of the dugong, the province's state icon.
Ready to start island-hopping? Here are five of Trang's top destinations.
Trang's biggest island, measuring some 40 square kilometers it's large enough to warrant a small paved road network, which runs around the island's coast.
Best traversed in a rented Thai-style sidecar (300 baht or $8/day), cruising along you'll come across small fishing communities and pass through rubber plantations (the two industries remain the biggest employers on the island, despite the gradual encroachment of tourism), while meeting some of the 6,000 friendly locals.
Accommodation is simple, with basic air-con rooms at the Libong Relax Beach Resort running at 2,000 baht (about $58) per night for a double room during high season.
All the resorts can arrange a longtail boat to see Libong's endangered dugongs (1,200 baht or $35/3 hours).
One of Thailand's last wild populations, they graze on the sea grass found in the shallow waters around the island.
Most Koh Mook visitors head straight for one thing -- the "secret" beach inside Morakot Cave.
Surrounded by soaring cliffs and accessible only at low tide, the beach is your reward for swimming through an 80-meter-long sea cave in pitch black darkness, led by a local guide.
The sunlight from above creates the water's distinctive emerald-colored hue and explains how the cave earned its name -- morakut is the Thai word for emerald.
According to local legend, the beach was once a secret hideaway for pirates, who came to hide their ill-gotten gains and escape the long arm of the law.
Koh Mook has several modest resorts to choose from, including the Sivalai Beach Resort (5,000 baht or $146/night), which occupies a stunning promontory on the east coast.
Perhaps the most famous of all the Trang islands, Kradan is being heralded as Thailand's next big thing.
A slew of resorts already occupy the east coast of this slender island, including The Sevenseas Resort (5,000 baht/night), with its boutique Robinson Crusoe vibe, and the private beach club at Anantara Si Kao (4,200 baht or $123) -- guests staying at the luxury resort on the mainland have access to this club.
The reason Kradan has the most hotels of Trang's islands becomes clear the moment you step ashore.
The stark white sand and crystal clear waters are brimming with fish. You can snorkel right off the beach and at low tide can even walk out to the coral reefs.
Small Koh Ngai (also pronounced "hai" in the local Thai dialect) is technically part of neighboring Krabi province but best accessed via the piers on the Trang mainland.
Once a favorite of backpackers, who came to rough it on empty beaches, the inevitable arrival of more upscale resorts such as the Thapwarin (2,250 baht/night) means these days you can stay in more comfortable surroundings while still enjoying the wild nature found all around you.
Out of all the islands in the archipelago, Ngai has the most unspoiled jungle, home to monitor lizards, monkeys and a huge variety of birds.
Measuring just four kilometers by two kilometers, the southern portion of the island is covered in coconut plantations, while the hilly interior is crisscrossed by rough tracks -- perfect for hikes.
Koh Ma, Koh Chueak, Koh Wan: The three where a dangerous foraging job awaits
Although too tiny to house any kind of accommodation, the sheer cliffs of these three small karst outcrops mean they're almost completely inaccessible.
As you float around them in a longtail, you can see small huts on top, with thick ropes swinging down in the sea breeze.
These belong to locals, who use them to search for the edible nests of the swiftlet birds.
The nests are exported to feed the insatiable Chinese market, including Hong Kong, which consumes more than 100 tons of them a year.
A single kilogram of bird's nest goes for more than $1,400.
As you can't go ashore on these islets, the next best thing is to go snorkeling in the waters around them -- though watch out for the strong currents.
Longtail boats can be hired from any island for around 3,000 baht or $88 for a half-day trip. Local lunch and snorkeling equipment included.
The closest international airport to Trang's Islands is Krabi, which offers direct flights to cities throughout Asia.
A handful of direct domestic flights to Trang Airport arrive via Bangkok daily.
To get to Koh Mook, Koh Kradan and Koh Ngai, it's less than two hours' drive from Krabi Airport to Kuan Thung Khu Pier, followed by a one-hour boat ride. Public ferries, private speedboats and longtails are all available.
To reach Koh Libong, drive a little further south to Hat Yao Pier, where local ferries make the short trip across the shallow waters.