Sala Khaoyai Villas by onion: A Minimal, Nature-Immersed Retreat in the Mountains of Thailand

Sala Khaoyai Villas, designed by the Bangkok-based architecture studio onion, represent a serene and contemporary hospitality experience located in Nai Mueang, Thailand. Completed in 2021 as the second phase of the resort, this 2,450 m² expansion reimagines luxury in the mountains by merging architecture, landscape, and atmospheric design. The project includes a selection of refined room typologies: a three-bedroom Pool Villa, two Pool Villa Suites, and three Pool Villas, alongside a dramatic mountaintop swimming pool open to all guests.

The leitmotif of the project revolves around uninterrupted views of Khao Yai National Park, the play of natural light, and fluid transitions between indoor and outdoor spaces. Every element—from masterplanning to furniture design—embraces nature, softness, and sensory calm.

A Mountain Retreat Designed Around Sunrise and Landscape

Unlike the resort’s first phase, which faces the sunset, almost every villa in this second phase is oriented toward the sunrise. This strategic orientation allows guests to start their day with expansive views of the shifting morning light across the mountainous terrain.

The only exception is the iconic 3-bedroom Pool Villa, positioned on the highest point of the mountain with an immersive 360-degree panorama. This singular vantage point transforms each room into a viewing chamber of Thailand’s dramatic landscape.

The architecture draws inspiration from the fluid silhouettes of nearby mountains, the contours of the land, and the naturally organic lines found throughout the site. Buildings appear to grow from the terrain, blurring boundaries between built structure and environment.

Guests first encounter the resort through an open-air pavilion crafted with earth-tone materials and bamboo ceilings, setting a grounded, nature-connected tone for the stay ahead.

Soft Interior Architecture: Curves, Light, and Seamlessness

onion’s interior design approach prioritizes gentle forms and soft shadows, echoing the natural surroundings. Every suite and villa features curved walls, rounded corners, and an off-white palette that blends walls, floors, and ceilings into one continuous envelope. By removing sharp angles and joints, the architects introduce a calming, cave-like atmosphere—an architectural quietness.

Light becomes a major design tool. Daylight filters across curved surfaces, creating a dynamic play of soft shadows throughout the day. All room layouts face east, giving each bed the prime view of the landscape at dawn.

Standalone bathtubs placed near windows and mirrors turn bathing into an immersive viewing experience—one where sky, mountain, and reflection converge.

Crafted Details and Materials Inspired by Khao Yai’s Soil

Every piece of oak furniture is custom-designed with curved edges. The bathrooms feature freestanding circular walls clad in small white marble tiles, adding texture and elegance without disrupting the architectural softness.

The textile palette is dominated by bright earth tones, complemented by a hint of soft pink—a color inspired by the natural soil of Khao Yai, adding a subtle sense of place.

Outdoor Living: Platforms, Rooftops, Pools & Stargazing Decks

The villas are composed of layered outdoor experiences, intentionally hidden from the main passages to maintain privacy and tranquility. Each villa includes:

• A sala pavilion
• Daybed areas at both the entrance and the rooftop
• Private swimming pools
• A mountain-edge outdoor bathtub platform
• Open BBQ spaces for fire-grilling

These programmatic elements encourage guests to live outdoors—to bathe under the sky, enjoy sunrise on a daybed, or star-gaze from the rooftop.

The 3-bedroom Pool Villa elevates this experience with an expansive 200 m² open-air living room, a 14-seat dining table, a working corner, and a spacious pantry. Each bedroom faces a different direction, giving guests a new scenic experience each morning. Loose pieces of furniture in the living area allow visitors to rearrange seating to discover different views.

A sculptural spiral staircase leads to the villa’s private rooftop, offering one of the most dramatic 360-degree views in the entire region.

Pools as Sky Mirrors

The villas’ private pools are designed as visual extensions of the sky. Guests can “walk on clouds” in the shallow areas or swim along the horizon in deeper sections. The architecture creates continuous reflections, enhancing the magic of sunrise and sunset moments.

The resort’s main swimming pool, located 250 meters downhill, stretches 32 meters toward the sunset. This long, linear pool merges seamlessly with the sky, emphasizing the vastness of the surrounding mountains.

An 80 m² open-air pool bar features a reflective mirror wall that intensifies the experience of observing the sun disappear behind layered mountain silhouettes.

 A Holistic Mountain Retreat Rooted in Landscape and Atmosphere

Sala Khaoyai Villas by onion redefine hospitality through minimalism, softness, and complete immersion in nature. From the masterplan to micro-details, the architectural language celebrates landscape, light, and sensory calm. It is a retreat crafted not just for relaxation but for contemplation—inviting guests to slow down, reconnect with the natural world, and embrace the poetic serenity of Thailand’s mountains.

All  photograhs are works of  W Workspace