Warm volcanic mud, herbal steam, waterfall rinse — the Samui half-day most Klook itineraries skip.
Namuang isn't a tourist gimmick — it's a working spa built next to the volcanic mud pools at the base of the waterfall. The mud is warm because the ground under it is warm; nothing is heated in a boiler. You paint it on (or the staff paint it on you), sit for 20 minutes while it dries, then rinse in the herbal steam room, then walk 100 metres to the Namuang waterfall for a proper cold-water rinse.
Two departures a day so you can pick morning (cooler, less crowded) or afternoon (pair with a Namuang waterfall walk after). Both are half-day with round-trip hotel transfer included; the whole thing takes about four hours door to door, of which roughly ninety minutes is on-site.
Kids as young as four can do it. The mud is safe on skin (patch-test if you have very sensitive skin). Bring a swimsuit; the spa provides towels and freshwater rinse.
The mud pools sit over a warm-ground vent — not a hot spring in the Iceland sense, but the mud comes out at about 35°C, which feels warm on the skin. It's the mineral clay that people go for, not the heat.
Swimsuit under regular clothes. The spa hands you a robe for the walk between the mud pool, the steam room, and the waterfall rinse.
Consult your doctor first. The steam room is not recommended in pregnancy; the mud bath alone is usually fine.
Access is included but the walk to the waterfall itself (about 300 m from the spa) is on you. Take 20 minutes for the walk plus another 15 to swim under it — the freshwater rinse after the mud is the whole point.