There’s a wildness about the back shore of Great Cranberry Island.

First, you take “I-95,” as islanders call it, a mile-long dirt road pitted partway with potholes opening up into a vast heath. Lush banks of bayberry border the track. Spirea, sweet gale and Labrador-tea bloom in the bush. The scarlet flower of a pitcher plant glints in the sunlight.

The wild, outback quality of Great Cranberry’s western shore drew Owen and Janet Roberts to the island 26 years ago. Owen Roberts, a retired diplomat wearing a white-and-black checked wool shirt and tan Dickies, tells the story as he navigates the first leg of I-95 in his gun-metal gray, 1980 Toyota pickup.

“We came looking from Washington, wanting privacy. There is some of that in Maine but not very much,” recalls Roberts, whose last diplomatic posting was as U.S. ambassador to the West African nation of Togo.

Pointing out a rise dubbed “Refrigerator Hill,” Roberts explains how there used to be an 8-foot dropoff where the ledge quit and the bog began. Old fridges were piled up to fill the steep ravine long before any environmental regulations. A corduroy road of spruce logs fords the swampy land.

Cairns — heaps of “trophy” stones dug out to smooth the road — stand like sentinels signaling the final stretch to the Robertses’ summer home. The modest, cedar-sided house sits amid towering spruce on a peninsula facing the Western Way. The smoky blue Mount Desert hills rise to the north.

A ramp, built for trundling firewood in a wheelbarrow, leads up onto the deck of the two-story home. Inside, a fire crackles in the fireplace made of beach stones. An old timber, cast ashore and worn to a silver sheen by the elements, forms the mantel. A firewood box is cleverly concealed in a driftwood seat.

A trim woman with pale blue eyes and salt-and-pepper hair, Janet Roberts is a ceramist and sculptor. She created the stoneware chess set on the coffee table and the kitchen tiles featuring drawings of native plants and family members. The island’s back shore has been a haven for her artwork.

“It’s so quiet and so beautiful,” she muses.

The Robertses discovered the Cranberry Isles, a cluster of five islands off Mount Desert Island, 30 years ago. They had just returned to Washington, D.C., after a three-year stint in the Belgian Congo, now Zaire.

“One March day, I was sitting in the State Department cafeteria and we got to discussing summer vacations,” Owen recollects. “William Dunbar, a spare, steel-rimmed Boston type with a slow, deliberate manner, suggested we rent his place on a Maine island.”

Bear Island, which boasts a lighthouse and is the smallest of the Cranberries, proved to be good training for the Robertses. They had to pump their water by hand from a dug well and fetch mail and provisions by boat from the mainland. But they enjoyed the rugged lifestyle, spending several summers on the tiny isle before searching for their own place.

“We were looking for sanctuary,” Janet says. “But either we couldn’t afford prime shorefront or we didn’t see anything we liked.”

Janet discovered Great Cranberry’s back shore while on the prowl with a real estate agent in a Boston Whaler. The property had been advertised in The New Yorker for years but the swamp had discouraged any takers.

The agent told her, “It’s nice, but you can’t get there.”

Undeterred, Owen, Janet and their teen-age son, Read, ventured over to Great Cranberry and found their way to the island’s western side. Along the way, “there was very deep, tea-colored water and we hopped from tree trunk to tree root.”

In 1973, the Robertses bought an 11-acre parcel on the back shore. The next summer, they turned Read and his cousins loose to clear land for a house and road. The boys were left with a tent, canoe, lanterns, chain saws and a supply of canned goods.

“They were just delighted with miles of forest to take down and road to build,” says Janet, chuckling. “I credit this project with keeping the Roberts children off drugs. They were too busy in the woods to be horsing around.”

Still living in Africa, with only a few weeks vacation per year, the Roberts saved time and money and bought a pre-cut home. They chose a Garrison-style house produced by Lindal Cedar Homes in the Pacific Northwest. The numbered Western red cedar boards arrived by freight train in Ellsworth and were barged directly to the remote peninsula on Great Cranberry. A Lindal crew spent several months assembling the structure, putting it together like an Erector set.

Over the years, the Roberts home has blended in with the scenery. The house sits on an outcropping of ledge carpeted with low-bush cranberries. Its cedar siding has been weathered by the elements, turning from silver to charcoal gray, as the sun circles the house.

In the living room, the walls were stained a birch color in keeping with the timber and driftwood furnishings. Mementos from the family’s years in Africa are everywhere. An ostrich egg, cream-colored and smooth as ivory, graces the mantel. A python skin flanks a wall. A bridal blanket from Timbuktu serves as a door. The exotic pieces seem at home in this rustic setting.

Upstairs, in the master bedroom, shaggy Finnish rugs cover the hardwood floor. A small balcony offers glimpses of the sea amid old spruce. A green Jotul stove cuts the chill of fall. Firewood is stored in the closet.

Early morning light floods a back bedroom. Its balcony overlooks the heath where cinnamon ferns and skunk cabbage unfurl, and yellow warblers, white-throated sparrows and other birds break the silence with their song.

Outside, you won’t find any lawn or perennial beds. The Robertses see the 165-acre wetland as their garden to tend. They have sought to preserve the wildness that first lured them years ago. Blow-down from winter gales has been cleared, allowing native plants to breathe and thrive.

Rose pogonia, a bog orchid with a single pink flower and fragrance like raspberries, is among the diverse flora that draws the eye.

“I make some aesthetic decisions, but not many,” says Janet Roberts, referring to the land surrounding her home. “I like to see what nature is doing.”

Owen is the frontiersman. Much of his time on the island is consumed felling dead trees. Working alone, he saws the downed timber and uses the logs to beef up I-95 and create paths like “495” winding to the shore.

Last year, on I-95 alone, he put in 17 eight-hour days.

“The nice thing, compared to the State Department, is that I can work at my own pace. I don’t have to clear it with anybody,” remarks the former Foreign Service officer.

This year, for his 75th birthday, he gave himself a four-wheel-drive, 25-horsepower BW8200 Kuboda tractor for toting logs and gravel. He also treated himself to six loads of fill and a construction crew barged out from the mainland to finish off the final stretch of I-95.

In all his woods work, Owen always takes time out to enjoy the wild scenery around him. He leads the way down to the shore where beach peas are in bloom. He marvels at tiny bits of garnet, embedded in great slabs of sedimentary stone, sparkling in the sun.

To the south, ocean swells roll in and break over South Bunker’s Ledge, marked by a red spindle.

“We really, simply, like being here,” he reflects.