The Anantara Peace Haven is no ordinary spa retreat. Tucked away on a rocky outcrop of the Sri Lankan coastline, the soon-to-open resort is marketing itself as a place of sanctuary – somewhere to take refuge from a hectic lifestyle and immerse oneself in a different world.

So far, so typical spa spiel. However, what sets Anantara apart is its integration into its surroundings. A 42-acre coconut plantation with views looking out onto the Indian Ocean, traditional Sri Lankan architecture and a menu of ancient Ayurvedic therapies, make it hard to imagine its underlying concept being transferred anywhere else. This is a far cry from the drably interchangeable spas that crop up in hotels around the globe.

But, we may be approaching a tipping point where exceptions of this kind become the rule. Today’s spas are less likely to be viewed as an optional amenity where ladies who lunch can enjoy a fluffy bathrobe and cucumber slices over the eyes.

These days, the patrons are just as likely to be trying out a mindfulness class, or be male and have booked in for a session of ‘Brotox’.

"Historically, the spa has been somewhat of an afterthought for some developers, but this is no longer the case. The spa and wellness facilities are now at the very forefront of the client’s and the designer’s minds," says Kevin Scholl, senior vice-president of architecture at WATG, the lead architectural firm behind Anantara.

"Destination spas are going to become the norm – spas that have hotel rooms, rather than a hotel that has a spa amenity – and the wellness philosophy encompasses the whole environment of the resort."

According to the media and marketing company Spafinder, which compiles an annual forecast of global wellness trends, the industry has been moving away from pampering towards something more diversified and holistic. For instance, its 2015 report lists what appear to be unorthodox trends such as cannabis-based wellness products and forest bathing.

Whether these fads take off or not, there can be no doubt that the very concept of wellness has led to a shift in people’s leisure habits. The strategy wing of WATG has undertaken detailed research into the sector and has noted a growing focus on authenticity – such as ‘back to nature’ and ‘digital detox’.

This is counterbalanced by various high-tech creations such as Stay Well by the real-estate developer Delos. These are hotel rooms specifically designed to provide a healthier stay currently found in hotels such as the MGM Grand Hotel and Casino in Las Vegas.

Asia, for example, is known for its hot mineral spring spa resorts, and Europe for its thermal experiences and thalassotherapy pools.

"They feature 20 evidence-based health and wellness elements including vitamin-C-infused showers, energising light, dawn simulation, warm white room lighting and blackout shade elements," explains Jeanie Klueter, director of spa and wellness design at WATG.

"The concept may one day be the norm not just for wellness resorts but all resorts in general, creating physical and emotional well-being for the travelling guest."

On the case

Evidently, modern spa design is difficult to generalise. WATG has designed spas as far afield as Bali and Arizona, with Middle Eastern projects including Four Seasons properties in Doha and Dubai, Abu Dhabi’s Emirates Palace and Atlantis, the Palm and works on a case-by-case basis, carefully analysing the local culture before beginning.

"People go towards luxury, tropical destinations for spa retreats and the urban spas are more tailored for a quick hit," says Scholl. "Extracting traditional spa and healing methods will help create a sense of authenticity and assist in addressing the specific needs and requirements of the place."

Asia, for example, is known for its hot mineral spring spa resorts, and Europe for its thermal experiences and thalassotherapy pools. In the Middle East, privacy is essential between the male and female guests, and many spas have a duplication of areas, right down to the reception.

The US meanwhile, has perhaps been unfairly maligned; stereotyped as offering little more than the typical ‘sauna-steam-whirlpool’ package. In actuality, there has been a surge of interest in the acronymic root of spa – salus per aquam – health through water.

Some of this variation also depends on the sophistication of the local market. While mature markets such as Asia are constantly looking for new ideas, the likes of Abuja, Nigeria – where WATG has a project under development – are still building on their leisure and tourism offerings.

"It’s almost like they are starting from the bottom," says Scholl. "They will need to start attracting an interest in spas and build a local clientele. By following these steps, they can then make a push to expand and grow."

For the London-based firm GA Design, developing a sense of place is critical to giving design longevity. The firm eschews anything overtly faddy, instead building narratives that work with the personality of the hotel.

"We often look to the surrounding environment, or the traditions of that area for inspiration, and then incorporate those elements subtly into the rest of the design," says Joanna Biggs, associate director. "This may mean sourcing local marbles and stones, or incorporating local decorative techniques and motifs into the millwork or furniture."

Treat yourself

While GA Design has a number of hotel spas to its credit – including Le Spa at the Four Seasons Marrakech, the Evian spa at the Palace Hotel Tokyo, and the Eforea spa in the Hilton Istanbul Bomonti – it is perhaps best known for the ESPA Life at the Corinthia London. With 17 treatment rooms spread over four floors of the hotel, this is one of the largest spas in Europe and it has won numerous awards.

"The design direction was developed together with ESPA, to challenge the typical spa interior," says Biggs. "We felt very strongly that relaxation was at the core of the concept and to achieve this, we created a soft, organic, gentle feel. When we broke this down into forms in the planning stages, it immediately took us away from boxes and hard corners towards softer, sweeping curves."

There is a certain style that people are now aiming for. It’s no longer the Bali or Asia-themed spa design; it’s more contemporary – clean lines and recess lighting used in the interior design.

In practice, this meant womb-like, elliptical treatment beds and pods for fitness, treatment and changing. Even the curves of the corridors recapitulate the theme. "You can feel the energy in ovals as you move around the spa," says Biggs. "It was a lotus flower shape that inspired them."

WATG largely works on the basis that, for a wellness resort, less is more. Klueter points out that while a resort should never be so simple that it comes across as clinical, it is imperative that all finishes and materials are perceived as clean.

"There is a certain style that people are now aiming for. It’s no longer the Bali or Asia-themed spa design; it’s more contemporary – clean lines and recess lighting used in the interior design," she says. "Textured walls with patterns add character to simpler rooms but operators may steer away from design elements that take too much time to maintain."

She credits the Hotel Therme Vals in Switzerland with spearheading this trend. Opening in 1996, the spa is built from layers of locally quarried slabs and is designed to resemble an archaeological site or cave.

Architect Peter Zumthor said of his then-radical design, "Mountain, stone, water – building in the stone, building with the stone, into the mountain, building out of the mountain, being inside the mountain – how can the implications and the sensuality of the association of these words be interpreted, architecturally?"

There is a curious contradiction at the heart of spa design in that, while the pace of change is rapid, it is often the most forward-thinking designs that call back loudest to the past.

A spa that pays homage to local tradition and the natural environment is likely to age well, even as trends come and go. It may well need a strategy to accommodate the unforeseen, leaving room for future expansions, and upcoming treatments and technologies. But it will need to ground itself in something beyond fashion; after all, a spa that looks noticeably cutting edge in 2016 may come to seem dated rather quickly.

Ultimately, spa-going rests on a simple and even primal desire to slow down, recoup and reconnect with oneself away from life’s stresses.

"I think, in the high-end luxury sector, guests are always looking for the ultimate pamper platform and we are constantly aiming to provide this. Every view should be considered, finishes carefully selected to promote relaxation, the perfect lighting, and, of course, ultimate service," says Biggs. "But in design terms, the knack is to make the guest feel like they are in their own space without having to be alone."