Khun Thale Swamp is a marshy wetland south of Surat Thani's centre, long used as a local fishing area. It is not a manicured park, but the open water, reeds, and birdlife give you a different view of the city from the usual ferry-ticket and night-market circuit.
Go for a quiet walk or a look at local life around the water. Conditions can change with maintenance and weather, so treat it as a flexible stop rather than a fixed-plan highlight.