Wat Sai is an ancient temple located in the heart of Surat Thani Municipality. It is believed to have been constructed during the Srivijaya Kingdom between 1300 and 1800 AD, and is associated with the nearby Wat Klang (Old Temple) and Wat Phra Yok. The highlight of this temple is the sermon hall, which is over 100 years old. Built in 1932, it is a two-story wooden structure measuring 12 meters wide, 28 meters long, and 18 meters high. The hall is constructed using top-quality hardwood and traditional timber joining techniques, showcasing meticulous craftsmanship.