At 247 km², Samui is the second largest island in Thailand and the largest island in an archipelago of over 80 (mostly uninhabited) islands which form the Ang Thong National Marine Park, a kayaking and snorkelling paradise. At 25 km (16 mi) long and 21 km (13 mi) wide, Samui is big enough for serious exploration by the adventurous and fit, but can be circumnavigated in just a couple of hours by motorbike or car.
Samui is home to some 50,000 full-time inhabitants, 90% of whom are Buddhist. The island was probably first inhabited about 15 centuries ago, settled by fishermen from the Malay Peninsula and south China. The origin of the name Samui is unknown.
Until the late 20th century, Samui was an isolated self-sufficient community, having little connection with the mainland. The island was even without roads until the early 1970s, and the 15 km (9.3 mi) journey from one side of the island to the other involved a whole-day trek through mountainous jungle.
In the early 1970s the first backpackers travelling on the back of a coconut boat arrived on Ko Samui. For years after that the island just had a few bungalows and a trickle of travelers. Things started to change in the early 1990s when tourists started arriving in full boats and since then the place has grown substantially. Samui is now the second most popular island destination in Thailand (after Phuket). Ko Samui may not be the country’s most beautiful island but it is still an oasis of natural beauty with its white sandy beaches, dazzling coral, luscious lagoons, picturesque waterfalls, swaying coconut trees, and crystal clear water. The water at Bophut Beach, though, is often murky, especially around December.
Development on Ko Samui has taken its toll and, before COVID, the island saw an average of 2.3 million visitors per year and the beaches of Chaweng and Lamai were overcrowded in the high season. However, the pandemic and the resulting border closures hit the local economy hard, with many hotels, restaurants and other businesses closing. If you can navigate the considerable bureaucracy to get to Thailand, the time to visit is now — it's unlikely the island will ever be this quiet again.
Samui's weather patterns are a little different from the rest of Thailand. In Apr-Sep, when most of the country has its monsoon, Samui stays fairly dry, but from Oct-Dec, it's wet in Samui and drier elsewhere. The best time to visit is January and February, when it's dry and slightly cooler.
Ko Samui, like other places on the Gulf of Thailand, has an unusual 12-hour tide pattern. During summer the tide is low at daytime and high at night time, while in winter it is always high at daytime. Beaches are much wider at low tide, and the difference can be huge in places with shallow water. In some places the beach may be very narrow during high tide.