Because of the commanding presence of Jørn Utzon’s iconic Sydney Opera House, few visitors to Australia ever bother to discover the other two great harbors of this Pacific Rim city: Pittwater to the north and Port Hacking to the south. But the locals know better. Though directionally distinct, the harbors’ similarities make both much-sought-after sanctums. Both are about an hour’s drive from downtown Sydney. Both have palm- and eucalyptus-shaded shores dotted with weatherboard cottages and brick mansions. And perhaps most important, both are occupied by residents who have found fragments of paradise.

Some of the luckiest watersiders call Great Mackerel Beach home. Accessible only by water or (impractically) by hours of bushwhacking down a steep cliff, this village on Pittwater is a haven for the adventurous.

To get to Mackerel, you have to take a chugging ferry from Palm Beach, near the tip of Sydney’s northern peninsula, across the bay. On the other side, you’re deposited at the end of a long jetty that leads to the center of the beach. Upon arrival, you can simply drop your bags in a wheelbarrow conveniently provided for locals and guests. It’s also here that you might spot architect Rob Brown and furniture designer Caroline Casey and their kids in the garden of their simple but stylish shack, famous locally for its quirky tree house.

From Brown and Casey’s abode, it’s an uphill climb to the residential enclave they’ve created in collaboration with their clients and friends, Marcia and Dougal James-Robertson. Set high on a cliff along the south end of the beach, this residence of three glass-and-copper pavilions offers a mighty reward for conquering the steep ascent.

When you arrive at the base of the James-Robertsons’ site, you understand immediately why the locals call it Alcatraz. Towering above you like the isolated island prison in San Francisco Bay is a massively intimidating wall of stone—a formidable barrier that must be overcome to reach the peak. Retaining the entire property from potential landslides, its ten-foot-thick walls were built with 11,000 chunks of sandstone excavated directly from the 50-degree slope. To meet the city council’s stringent anti-noise requirements, the edifice had to be constructed without any mechanized tools. As Rob Brown recalls, “For over six months, the stonemasons were literally chipping away at the stone all day—the place sounded like Carrara.” Adds Marcia, “Our builder had 22 laborers walk off this job—the site was so steep and difficult.”

But the work was well worth it, which becomes exceedingly obvious as the home reveals itself during your journey up. A flat path of timber boards, bordered with white gravel, leads you around the back of a steel-framed glass shed that hovers lightly above the ground. From here, turn a corner and step up more treads of sandstone to a timber deck that floats between two of the three transparent pavilions. Ahead lies an astounding aerial vista normally familiar only to pilots and birds. The expansive bay of Pittwater, dotted with yachts, stretches out below, while the flat ribbon of the northern peninsula, with its bush-clad headland, slices through the blue waters. The lush land is topped by the blinking Barrenjoey Lighthouse—and beyond, the vast Pacific meets the sky.

Safely ensconced in what they tellingly refer to as their “glass tents,” Marcia, a property and lifestyle analyst, and Dougal, a wine importer and distributor, are at one with the mysterious weather patterns in the midst of this awe-inspiring scene. Former owners of a viewless cottage near Mackerel’s village green, their perception of nature has changed dramatically since moving into their new house. These days, it’s not about watching ducks frolicking in the creek, or listening to possums stalking the trees and roofs at night. Now the James-Robertsons marvel at nature writ large. “The doors are open and there’s a northeaster blowing,” Dougal says. “The colors of the sky and the qualities of the light are always different. The moods are amazing.”

Their home’s trio of skillion-roofed sheds fits within the high-tech modernist style of architecture that emerged in Sydney during the 1980s and ’90s, following Pritzker Prize–winning architect Glenn Murcutt’s adaptations of Mies van der Rohe’s classic glass box.

The James-Robertson house pays obvious homage to Murcutt’s (and Mies’s) work but includes a number of innovations, including the use of corrugated copper roofs on the pavilions and on some wall panels. Aside from its structural appeal, one big advantage of this material is its red-brown patina, which blends with the muted natural colors of the land—a blessing for neighbors whose homes overlook the property from higher up the hill.

With the buildings’ black aluminum-and-steel frames, the red-brown of the copper, the teak timber decks, and the landscaping of the arrival path, the architects have created a sense of both naturality and nauticality. There’s an atmosphere that links the architecture and quintessentially Australian location and light qualities to certain ancient sensibilities of Japan. At night, indirect lighting from fixtures installed along select roof eaves and interior walls increases the drama.

Inside, the house is less precarious, though no less dramatic. The side-by-side living pavilions contain a guest suite, study, wine cellar, and plant room on the ground level, with living, dining, and cooking areas above. The upper sleeping pavilion contains a laundry room on the lower level and a master bedroom above.

Interiors are furnished with only a few pieces of freestanding furniture, designed to float above the floors to enhance the impression of continuous space. Caroline Casey, Mackerel Beach’s star furniture designer, however, was still able to contribute quite a bit to the project, designing the couple’s dining table, bed, and cabinetry and bringing in a unique personal flavor. Also notable is the custom-made fiber-optic barber pole light sculpture installed on the main deck: Its programmable effects of colored light can be seen from the mainland and tip a wink to the historic lighthouse at the tip of Barrenjoey headland.

Apart from an Alvar Aalto leather sofa and armchair and dining chairs by Marcel Breuer and Hans Wegner, all other furniture is wall-mounted to free up floor space. The most prominent installations are the fireplace and stereo cabinet, with its sliding doors of stainless steel mesh, and the stainless steel cabinets and shelving in the kitchen and walk-in pantry. Terrazzo basins and showers of floor-to-ceiling frosted glass round out the bathroom.

Loving their new life on high, the James-Robertsons still commute to their professional roles in the city, lugging their briefcases and laptops along the beach to the ferry or water taxi. But when they get home, they open themselves to the weather. As Dougal explains, “We’re just living from day to day here. We open all the glass doors so we’re fully and completely in touch with whatever’s happening outside. You definitely need a sense of adventure, but really we’re living in a dream.”