Koh Samui: The Complete Overview

Koh Samui is an island in the Gulf of Thailand, off the east coast of southern Thailand. It belongs administratively to Surat Thani Province and lies about 35 km northeast of Surat Thani town. The island is roughly oval, about 25 km at its widest point, with a mountainous jungle interior and a paved ring road (Route 4169, about 51 km) that circles the coast and links all the main beach towns. Its area is officially quoted as 228.7 square kilometres; older tourism texts say 247. Sources also disagree whether it is Thailand's second- or third-largest island after Phuket - both claims are recorded in the geography category. Around 70,000 people are registered as residents, but with migrant workers and tourists the real number of people on the island is much higher.

Why visit: Koh Samui combines an easy, developed holiday island with real Thai island life. It has about 35 documented beach areas, all public by law and free; famous temples such as the 12-metre golden Big Buddha (1972) and the colourful Wat Plai Laem, all free to enter; jungle waterfalls; lively night markets; and simple day trips to Ang Thong National Marine Park (42 limestone islands), Koh Phangan and the diving island Koh Tao. The island has its own airport (USM), hospitals, malls and every level of accommodation, which makes it easier for first-time visitors than most Thai islands.

When to come: the driest, calmest months are roughly February to April; April is the hottest. May to September is a warm shoulder period with short showers and lower prices. October to December is the wet season, with November usually the wettest month - ferries can be cancelled and Ang Thong Marine Park usually closes from 1 November (2026 reopening date not yet confirmed)^[1]. Samui's rhythm is different from Phuket's: mid-year is often better here.

How it works in practice: you arrive by air at USM or by ferry from Donsak on the mainland, you get around by songthaew (shared red pickup trucks), negotiated taxi, Grab, or a rented scooter or car (left-hand driving), and you pay in Thai baht, with cash still essential at markets and for small transport. Daytime temperatures sit around 29-32°C all year and the sea is about 28-30°C. This master guide is the hub; the detailed answers live in the category files cross-referenced below.

1. [1] Tourism Authority of Thailand — national park seasonal closures · checked 2026-11-10