Thailand's Largest Islands Ranked by Size

Thailand's largest island and one of the country's most developed tourism destinations. Phuket combines beaches, resorts, urban areas, restaurants, and a major international airport.

Located in Surat Thani province, Koh Samui is Thailand's second-largest island according to DMCR data. It is a major Gulf of Thailand tourism destination known for beaches, resorts, waterfalls, and its own airport. 

Koh Chang offers size and variety, which help when the weather shifts. You find waterfalls, jungle trails, and indoor options such as spas and cooking schools. The island’s ferry links to the mainland run most days, which helps with flexible arrival and departure plans. Many bays provide shelter for short boat trips and snorkeling between showers. Budget bungalows and mid-range resorts stay open year-round, which makes Koh Chang a value choice during the rainy season.

Located in Satun province, Koh Tarutao is part of Tarutao National Park. Compared with Thailand's major resort islands, it offers a much more nature-focused experience.

Located in Surat Thani province, Koh Phangan is famous internationally for its Full Moon Party, but the island also has beaches, waterfalls, forests, and quieter areas away from the main tourist z

If you’re dreaming of Bali’s beaches before the boom, Koh Kood is as close as it gets in Thailand. This is a low-rise, low-key island with powdery white sand, glassy lagoons, and a handful of small resorts tucked into coconut groves. There’s minimal traffic, almost no nightlife, and a strong bring-a-book energy. Explore by scooter to find waterfall pools and quiet bays, snorkel vibrant shallows, and watch some of the clearest sunsets in the country. Access is by speedboat from Laem Sok Pier near Trat, and the best months are roughly November to April when seas are calm and skies are clear.