Chaweng Beach, Koh Samui's most popular and most developed beach, is surrounded by restaurants, hotels, and shopping. About 6 kilometers in length, it is an excellent beach for swimming.
Lamai Beach is the second most developed beach on the island, but offers a more low-key vibe. It's a less crowded alternative to Chaweng and offers some popular nightlife options.
If it's even more tranquility you seek, Bophut and Mae Nam beaches are your answer. Mae Nam is an unspoilt stretch of beach with little development. The pristine white sands of Bophut beach also features the Fisherman's Village, a well preserved example of village life on the island.
Water enthusiasts visiting Koh Samui won't leave disappointed. Scuba diving is one of the most popular water sports on Koh Samui, with several diving companies operating out of the island, but there are numerous other water activities on offer as well, including snorkeling, kayaking, windsurfing, sailing, jet skiing, and fishing.
For those of you who prefer your activities to be on solid ground, the Santiburi Samui Country Club boasts a championship golf course, and various spas and resorts on the island offer yoga classes and retreats.
Other, more unusual land activities include riding quad bikes in the jungle and firing an AK 47 on a professional shooting range.
Koh Samui has several Buddhist temples, including Wat Phra Yai with its large gold Buddha and the intricate Wat Ban Plai Leam temple, featuring a huge statue of the god Shiva. Wat Khunaram is a shrine to a highly regarded Buddhist monk, whose mummified remains are on display for visitors.
In the hills of Koh Samui, a Buddhist artist created sculptures based on images from his dreams and placed these sculptures along a mountain stream, creating what is known as the Secret Buddha Garden. Hat Ya and Hat Yin, two large, ancient rock formations that resemble the male and female genitalia, are another much-photographed site on Koh Samui.
There are also many waterfalls on the island, Na Muang falls being the most accessible.
Koh Samui is famous for its nightlife, which is concentrated in Chaweng and Lamai. There's a variety of bars and nightclubs to suit all tastes, and a trip to Koh Samui isn't complete without sampling some Mekong, the famous Thai whiskey.
There are also monthly outdoor parties, such as the Full Moon Party, where revelers dance the night away on the beach (the nearby island of Koh Pha Ngan, a short boat ride away, also hosts its own Full Moon party which has become world famous).
Chaweng Beach also features several cabarets, where you can check out a drag show performed by Thai Kathoey's, commonly referred to as ladyboys.