The Avatar Spa Mountain Suites in the wilds of northern Thailand breaks the mould by striking out in startling directions. Located in a tropical valley in the Ban-rai district of Uthaithani province, a three-hour drive north of Bangkok, Avatar takes its inspiration from the nearby Khao Pla Ra cave, which features black and red wall paintings dating to 3000 B.C. Step into the open-air lobby and you’re suddenly in the coolness of a cavern, even though the temperature’s peaking outside. Walls are dotted with copies of cave drawings — elongated Giacometti-like figures wielding bows and spears. Floor-to-ceiling openings in the walls frame views of the surrounding mountains. This is an ideal spot to find a comfortable seat on a balcony overlooking the lagoon, or up on the canopied divans on the grand terrace off the library, and drink in the silence and beauty. Three wings of guest suites fan out from the central lobby, and are surrounded by a lagoon that cools patios and balconies, and dapples the grey concrete walls with reflected light. The spa is in a separate, low-slung building close to a trio of freshwater, saltwater and “Dead Sea experience” pools. Avatar manages to bring cutting-edge architecture to an ancient valley without clashing with the scenery. Offering neither the studied opulence of a grand hotel nor the by-the-book minimalism of a standard boutique property, Avatar’s suites are ideally accessorized caves — dim, cool, large and cozy, all at once. The walls are soft grey with scattered cave paintings, and the careful positioning of the guest wings yields bright landscape tableaux out of generous windows. The ceilings in many suites are moulded to echo the curving unevenness of a real cave, and local hand-woven fabrics provide touches of rich colour. Low-slung beds and built-in sofas are offset by pieces of post-Second World War kitsch: a Mediterranean-style amber glass table lamp, a tufted leather divan. Many of the bathrooms feature outdoor baths set in private courtyards. Room rates include meals and a free mini-bar. The room-service breakfast is a must — it arrives at your shaded balcony courtesy of a bamboo boat that plies the waters of the lagoon. Al-fresco dining at the Skylight Restaurant, a raised concrete dais, delivers excellent Thai cuisine.