A real plunge, not a barrel
A tiled basin set flush into the teak deck, with an underwater bench and two steps — you sit submerged to the shoulders, two people side by side. Clear still water, a smooth unbroken surface.
4–6°C in a tropical garden
A concealed chiller in a service niche holds the water at 4–6°C around the clock. By the deck there is only a slim display with the current temperature — no machinery in sight.
The contrast routine
Sauna round, plunge, rest in the garden air — repeat. The hot-cold circuit is the daily ritual the whole complex is designed around, and the first thing renters photograph.