KRABI

Credit: borshop via Flickr

Koh Tup

This tiny island may be just a 30-minute longtail boat ride away from Ao Nang’s holiday crowds, but take a private boat and you stand a chance at avoiding the large tour groups. The island is linked to neighboring Koh Kai and Koh Mor by stunning sand bars, surrounded by blue waters filled with tropical fish—perfect for snorkeling.

Credit: Jani via Flickr

Koh Jum

Located right between Krabi Town and Koh Lanta, this peaceful little island is the perfect place to unwind. The vibe is lowkey, its beaches lined with trees and palm-roofed shelters with the odd monkey playing around. There isn’t a whole lot to do here except for sunbathing, water sports, and strolling along the beach, followed by a beer or two at a chilled-out reggae bar. The slow pace of Koh Jum will give you the chance to take a real break from the madness of modern life in a beautiful environment.

TRANG

Credit: Mike Locke via Flickr

Koh Mook

This unexploited southern island is crisscrossed by narrow dirt roads leading to mesmerising water caves and secluded beaches. Its claim to fame is Tham Morakot (Emerald Cave), where turquoise water guides you through a small opening into a secret lagoon with its very own beach. Far smaller and quieter than nearby Koh Lanta and Koh Phi Phi, this little gem makes for the perfect Andaman escape. 

Credit: Alessandro Caproni via Flickr

Koh Kradan

Located just southeast of Koh Mook, this postcard-worthy paradise offers everything from crystal clear water to white sandy beaches and—best of all—privacy. Surrounded by an untouched coral reef, this is the ideal destination for divers. Those who prefer to stay above board can rent a kayak and paddle around the island. 

RANONG

Credit: prilfish via Flickr

Koh Phayam

This remote, kangaroo-shaped island has a tiny rural population and has been hailed by some as the new Koh Samui (pre-Chinese invasion). It may not be “undiscovered,” per se, but it’s far enough from the typical tourist trails to avoid being overrun. Its winning combo of lush jungles, clear waters and amazing beaches like Ao Khao Kwai and Ao Yai make it a surefire hit. Koh Phayam is about as peaceful, quiet and relaxing an island as you can find in Thailand.

SURAT THANI

Koh Phaluai

Two hours by boat from Surat Thani, Koh Phaluai is the largest of the 42 islands in the Angthong Marine Park. The southern half of this undiscovered gem doesn’t belong to the national park, however, and that means there are a few bungalows and eco resorts among the fishermen villages where you can spend the night. Expect to hear little more than the sound of waves as you sunbathe, spot hornbills and picture what life was like before mass tourism. 

TRAT

Credit: Angela Symons

Koh Mak

Thailand’s eco island actively discourages hard partying, preferring guests that align with the local islanders’ sustainability-driven ethos. Located between Koh Chang and Koh Kood, this flat island filled with rubber, coconut trees and white sand beaches abides by a set of rules that include prohibiting foam packaging, discouraging engine-powered watersports and banning 24-hour convenience stores. Bye bye banana boats and 7-Eleven, hello island nirvana.

CHONBURI

Credit: Nida P. via Wikimedia Commons

Koh Munnork

It’s a bit easier to find serenity when you’re visiting an island with only one privately owned resort on it, like Koh Munnork. Located east of Koh Samet, this tiny sanctuary is only accessible by the beach resort’s boat. When you arrive, you’ll find “achingly beautiful beaches,” according to the property brochure, as well as 22 boutique bungalows (from around B3,000/night) backed up against the island’s native forest.

PHANG NGA

Credit: Rev Stan via Flickr

Koh Yao Noi

Partner islands Koh Yao Noi and Koh Yao Yai draw surprisingly few visitors considering their proximity to Phuket. While you can’t go wrong with either back-to-nature escape, Koh Yao Noi is our pick. You can easily traverse it in a day by bicycle, and after you’ve worked up a sweat pedaling between beaches or sea kayaking, you can retreat to a number of eco-minded spas and resorts, including Six Senses Yao Noi and 9 Hornbills, the new-ish luxury glamping getaway.  

SATUN

Credit: Vyacheslav Argenberg via Flickr

Koh Rawi

Little Koh Lipe gets all the attention, but neighboring Koh Rawi is where you really want to go. The beaches are like fine white sugar, the waters a very bright blue, and it’s almost completely uninhabited, apart from a couple of ranger stations. Hike through wildlife-rich jungle, cool off in one of the bays and, if you’re so smitten you don’t want to leave, pitch a tent.