Vihara Sanctuary

Vihara Sanctuary is a small sauna and spa retreat in Lamai, on Koh Samui's southeast coast, built around a sauna, steam room and ice bath set in a quiet jungle garden. What makes it unusual on Samui is the access model. The facilities are sold as a standalone day pass — around ฿380 — so you can use the sauna, steam room and cold plunge without booking a massage or treatment first, which is how almost every other spa on the island gates its facilities. A garden café serves smoothies, teas and simple wholesome food between rounds. The appeal is contrast therapy done unhurriedly — heat, steam, cold, repeat, at your own pace — rather than a scheduled treatment, and it is markedly quieter than the resort spas along Chaweng and Lamai beach. An easy stop after a day on the Lamai beaches, and one of the cheapest full facility-access sessions on Koh Samui.