Ever since man first discovered hot waters bubbling from the ground, thermal springs have been places of pilgrimage and bathing rituals have grown up around the springs’ mythic and therapeutic powers. The common ground in these contemporary interpretations from Japan to Europe to Chile, is their immersion in natural surroundings and their choreography of bathing rituals that reconnect us to the original meaning of spa (salus per aqua or ‘healing through water’).

1. Zumthor’s baths, built over the thermal springs at Grabünden, celebrate the local Valser mineral water and its majestic surroundings in a complete sensory experience that evokes the spirit of ancient bathing traditions. Built from local Valser quartzite, Zumthor uses only the most fundamental materials – mountain, stone, and water – to create a monumental and timeless structure where bathers can engage with the elemental nature of water and purity. The architecture creates the framework for bathing rituals, as the aquanaut roaming from chamber to chamber experiences different thermal and water sensations. Through careful orchestrations of natural and artificial light – as well as of shadowy darkness – by tightly framing views from the spa complex over the valley and by playing with the acoustics of stone and the sensorial qualities of steaming and bubbling water, Zumthor offers the bather a totally embodied experience. As well as setting an extraordinary benchmark in bathhouse design, Therme Vals, commissioned by the local commune, shows the possibility of public baths as an inclusive social project, designed to revitalise the local community and economy.

2. A rust-red timber walkway cuts through the winding canyon of the Villarrica National Park, renowned for its natural hot springs and active volcano. The walkway zig-zags 450 metres over surging river waters and waterfalls to allow bathers access to seventeen steaming pools, surrounded by lush forest foliage. Beside each pool is a shed with private bathrooms and changing rooms, as well as occasional open grass-roofed shelters where bathers can relax around an open fire. Architect Germán del Sol writes, ‘The geometric architecture of the Termas makes it possible to see and enjoy the good side of the unexpected events of nature.’ He describes the experience of bathing in Termas Geométricas as ‘a sensual rite of water and fire purification which enlightens our senses and arouses our imagination.’

3. Kogohi Bathhouse is an outdoor bath in Atami, the most celebrated hot-spring area in Japan, a country peppered with thermal waters caused by volcanic activity. Here Kengo Kuma uses minimal means – essentially a wooden deck and translucent canopy – to allow the lush, natural landscape to become the focus. The basic elements of bathing – a dressing room, a washing station where the bather balances on a small stool as she meticulously scrubs every inch of skin before entering the bath, and the large wooden onsen tub – are lined up in a row to take advantage of the sea views. Nothing is allowed to distract from the architect’s goal of offering the bather the sensation of floating weightless in nature. While the design appears effortlessly simple, every aspect of Japanese bathing culture from the quality of Yu (hot water) to the craft of making the bath from hinoki wood (cypress) has been refined over centuries.

4. Located in the hot springs of Takeda, Lamune Onsen (Soda Pop Spa) takes its name from a fizzy drink that resembles the naturally carbonated spring water found in the area. Fujimori’s invention of a folkloric Japanese vernacular for the design of the onsen is an antidote to the clinical style of much contemporary Japanese architecture. His poetic cocktail of influences range broadly from sixth-century Japanese temples, the Neolithic stones of Callanish in Scotland, Mali’s rammed-earth mosques and European thatched cottages. The resulting distinctive cluster of neo-primitive forms around an inner courtyard – is clad in charred cedar panels (a method of preserving wood) joined with white mortar, creating an uneven zebra pattern. The apexes of two towers that act as chimneys are planted with live pine trees as a symbol of prosperity. Inside sensually curved forms of the baths for women, men and families continue the organic design.