There is a strangeness about many pools i find in the tropics; they dont feel particularly pleasant to get into at certain times of the day. On the warmest days of the year, they dont feel quite nice even during the best times of the day. The problem lies in heat gain; most tropical pools are warm. Clingingly humid. Tepid.
The best tropical pools ive found have a crispness about them, a quick chill which then becomes soothing cool; pools of water commonly fed by higher altitude and mountain streams. The feeder streams of the Columbia River Gorge and Wildwoods in Oregon have absolutely lovely plunge pool water in summer, but like the lakes in the Northeast of America, are temperate. The river pools with almost perfect water must surely be those at Tirtagangga in Bali. Breathcatching for a brief moment on first entry, brisk bracing water under an equatorial sun. A touch colder than the breakers of Diamond Head in Oahu, warmer than late summer snowmelt in New Zealand.
The concept of the mountain pool is one designed for tropical application.
It begins by reducing the function of the tropical pool as a heat sink. By working shade around and over at least a third of the pool surface at any chosen moment of the day to keep a bulk of the water cool. It works best under the shade of trees, for the effect of fallen leaves and flowers on the surface of the water, streamlike in character, mottled shadows and bright flecks of sunlight at play. The mountain pool is about sun and shade, a balance of contrast and the balm of cold water on a humid sunstoked day.