Koh Samet
One of the closest destinations to Bangkok for an island escape, making it popular with Thai visitors, Samet lies 99 miles south of the capital (4.1 miles offshore). It is connected to the mainland by scheduled ferries and speedboats based in Rayong, a port city famous for its fresh seafood restaurants. You can get here by car or bus.The island is about four miles long and is as narrow as 500 feet where it tapers toward the south. While it is part of a marine national park, you wouldn’t guess that at Sai Kaew, where resorts cluster around the popular beach with a line of restaurants and nightly “fire shows”—young performers juggling or even spitting fire. Resorts farther away get quieter and are more relaxing, with a mix of rugged shoreline and short stretches of sand. The natural spaces are known to be rich with birdlife—birders have recorded more than 130 species.
Nearest airport: Bangkok’s Suvarnabhumi International Airport (BKK) (“Soo-wahn-a-poom”).


Koh Racha Yai
About a 45-minute boat ride from Phuket, this tiny island is actually the big (“yai”) sibling to the uninhabited Racha Noi (“small”) five miles away. Day trippers come to both islands for the snorkeling and diving, but lodging is limited to four resorts on Koh Racha Yai, and they are worth considering for a tranquil piece of paradise. Beaches are limited to two small, horseshoe-shaped bays with modest curves of sand between rocky outcrops, one of which lies right in front of the luxury resort, The Racha. You can walk to get access to the best snorkeling spots along the shore, and short hikes take you to scenic overlooks.Nearest airport: Phuket International (HKT)

The Islands of Trang
Southern Thailand shows an abundance of those magical karst formations, towering weathered limestone outcrops that look like a frosted cake melting in the sun, but may be covered or at least crowned with green jungle. When these formations are rising up out of the waves, they are even more entrancing. Such is the scenery in the Andaman Sea between Phuket and the province of Krabi, drawing abundant travelers.
But Trang Province, to the south of Krabi, offers the same while being a bit more off the beaten path. Off Trang’s shore is a scattering of islands, offering a range of experiences and accommodations from luxury resorts to simple cabanas or even tent camping.
Koh Mook is perhaps the best known of the bunch thanks to Tham Morakot, the Emerald Cave on the island’s west coast. Visitors come here by boat, but then must swim or paddle a kayak through a narrow 260-foot tunnel to get to a hidden beach surrounded by sheer limestone formations. Resorts occupy the other side of the island, along the idyllic white Sivalai Beach. The gently sloping seafloor makes this location great for families with kids.

If snorkeling is your jam, then the best bet here is Koh Kradan. A reef runs about 2 miles along the length of the island’s east coast, though the southernmost 0.8 mile is most notable and is easily reached from shore. Walk about 15 minutes through the forest to get to Sunset Beach at day’s end.
Koh Libong, the biggest and most populous of them. Rent a motorbike and tour the island. The waters here are home to the marine mammal, the dugong, a cousin to the manatee, which is listed as “vulnerable” (a step above endangered) for its declining population driven by a loss of habitat.
Nearest airport: Trang (TST)

Tarutao National Marine Park
Just off the coast in the Andaman Sea, the 51 islands of Thailand’s largest marine park are as far south as you can get in Thailand before you enter Malaysian waters. Boats depart from Pak Bara Pier stopping first at the largest island, Koh Tarutao, the location for “Survivor: Thailand” in 2002. Enjoy quiet beautiful beaches, hiking trails and overlooks, a historical prison and Crocodile Cave, a 900-foot deep cavern of stalactites and stalagmites where visitors follow boardwalks and even cross the water in a small boat as they explore with a guide.Despite this, most travelers stay on the ferry and continue to the westernmost islands of the park: Koh Adang, Koh Rawi and Koh Lipe (LEAP-ay), the latter being the smallest of the three and the most developed with resorts. This is also the place to hire a long-tail boat for a tour of the waters. Snorkeling here is some of the best you will ever find in Thailand and beyond. Koh Adang hosts camping near the park office, right along the edge of the beach.
Nearest airport: Hat Yai International (HDY).


Khao Lak and the Similan Islands
While not itself an island, Khao Lak refers to a beachside village and its surrounding area over an hour’s drive north of Phuket International Airport. This is the launching point for snorkeling and scuba trips to the Similan Islands, an archipelago within Mu Koh Similan National Park and currently being considered for UNESCO World Heritage Site status. Famous for pristine waters, abundant reefs and sea life, the islands only offer limited bungalow and campsite options on three of the 11 islands. The vast majority of visitors come on boat trips from the mainland. If group tours aren’t your thing, you can rent an entire boat with a captain and guide for a reasonable amount of money for the day. Be advised: Access to the islands is closed seasonally, from May 15 to Oct. 15, which roughly coincides with monsoon season.Khao Lak’s mainland beach stretches for miles, and the sandy bottom is shallow a long way out, making it great for beginning surfers. When the tide goes out for the sunset, the vast wet sands capture incredible reflections. Stay ashore and head up into the hills to visit a couple of scenic waterfalls or kick back and enjoy a tour of the jungle on a long bamboo raft. Using a pole, a local guide navigates the gentle riffles of a mountain stream and points out local wildlife.
Nearest airport: Phuket International (HKT)


If You Go
Most travelers will arrive in Bangkok at Suvarnabhumi International Airport (BKK) or with secondary airlines at Don Mueang International (DMK). Phuket (HKT) actually has more diverse international flights than Don Mueang, with some European airlines, and Samui Airport (USM) has very limited regional routes.All of the islands mentioned here have regular ferry services from the mainland, with inter-island routes as well. Speedboat transfers and private boats are also available, and, for an adventure, hiring a traditional long-tail boat for shorter distances is an unforgettable experience, if a bit noisy and slower than speedboats and private boats.