For a Malibu beach house he was designing in the 1950s, he took to the sea, paddling out on his surfboard to examine the property from a spot beyond the wave break. From there he made the initial drawings for what became his most famous building, the Wave House, using a grease pencil to sketch its curving, wavelike roof directly onto his longboard.
Mr. Gesner’s designs were variously inspired by the shape of a sand castle, the wings of a bird and the scales of a fish. Their unorthodox appearance reflected the adventurous spirit of a architect who once romanced actress June Lockhart while performing water-skiing stunts on Lake Arrowhead, and who later survived the D-Day invasion of Normandy with help from a surfing technique, duck diving, that he used to avoid enemy fire while making his way onto Omaha Beach.
Over the years, Mr. Gesner also worked as a deckhand on actor Errol Flynn’s yacht, searched for ancient artifacts in Ecuador, hunted for the grave of conquistador Juan Rodríguez Cabrillo and tinkered with inventions, designing a Kentucky processing plant in the 1960s that turned waste into fertilizer, and converting his 1957 Mercedes convertible into an electric car more than five decades after he bought it.
But mainly he designed homes, seeking to create environmentally friendly houses that served as a source of joy, not just as shelter. To that end, he often added surprises to his buildings: For the Scantlin House, located at what is now the Getty Center in Los Angeles, he designed a lap pool that stretched nearly 100 feet, culminating in a waterfall that concealed an underwater passage leading to the home’s master bathroom.
“You come around a corner, look down into an alcove and see something that pleases you … it takes the drudgery and dullness out of life,” he once told the Los Angeles Times, explaining his fondness for the unexpected flourish.
Mr. Gesner was 97 when he died June 10 at the Sandcastle, the mushroom-shaped home he built for himself in Malibu, right next door to the Wave House. The cause was cancer, said his stepson, Casey Dolan.
Although he took commissions all around the country, Mr. Gesner was best known for his mid-century designs in Southern California, which often featured curved walls, floor-to-ceiling windows and natural materials like Santa Barbara fieldstone and bird’s-eye maple. His houses were frequently located in unusual locations, embedded within a canyon’s narrow walls or thrust above a rocky beach.
“The challenge is what is exciting in architecture,” he said in a 2016 interview with the magazine Dwell. “People would always say, ‘Well this is a terrible lot. This is an impossible place to build.’ And I would say, ‘No — just watch.’ ”
To construct the Hollywood Boathouses, a series of more than a dozen angular homes that were cantilevered over the Cahuenga Pass, he sought out craftsmen who could work from the hillside suspended by ropes.
“By luck, I found a group of Norwegians shipbuilders who had been repairing churches,” he told the website Curbed. “They worked with hand axes and saws, and really didn’t speak English very well, except for one guy. But, they said they could do it, and for them, it was fun, just like building a ship in Norway.”
Mr. Gesner’s buildings earned him the admiration of architects including Jorn Utzon, who was said to have modeled his design for the Sydney Opera House in part after the Wave House, and Richard Meier, who lived at the Scantlin House and insisted on its preservation while overseeing the construction of the Getty Center.
His work also led to commissions by demanding clients. In 1980, Marlon Brando hired Mr. Gesner to renovate his Beverly Hills mansion and design an estate on Tetiaroa, the actor’s private atoll in French Polynesia, where Mr. Gesner developed plans for an island getaway that featured a roof covered in woven pandanus leaves, a floor crafted from polished coral and a 60-foot-long aquarium that the actor planned to stock with sharks and moray eels.
But the plans fell apart after Brando kept changing his mind on what he wanted, according to Mr. Gesner. In an interview with Architectural Digest, he described the actor as “very bedroom-oriented,” adding that their conversations were often interrupted by a female visitor: Marlon would disappear for half an hour. I would just sit there and read a book.”
As Mr. Gesner told it, he was unusually well positioned to become an architect, coming from a family with deep roots in art and engineering. His grandfather Alexander Harmer was a leading 19th-century painter of Southern California, and his uncle Jack Northrop was an influential aircraft designer who helped develop stealth planes and long-range bombers.
“The genes,” Mr. Gesner liked to say, “were all in line for me.”
The older of two sons, he was born Harry Harmer Gesner in Oxnard, Calif., on April 28, 1925. His mother was an artist whose great-grandfather had served the Spanish and Mexican governments as head of the Santa Barbara presidio, and his father was an engineer who raced cars, flew planes and surfed in Hawaii with Duke Kahanamoku. When he landed a job at Douglas Aircraft, the family moved to Santa Monica.
Mr. Gesner developed an interest in architecture while delivering newspapers, admiring the varied design of the homes on his paper route. He later filled notebooks with sketches of European castles and cathedrals that he saw while serving in the Army during World War II.
According to Lisa Germany’s book “Houses of the Sundown Sea,” a survey of his career, Mr. Gesner was wounded during an artillery attack in the Hürtgen Forest of Germany, and nearly lost both legs to frostbite before being sent home in 1944 to recover. He went on to study at Yale University, where he audited an architecture class and made drawings that impressed Frank Lloyd Wright, who invited him to study at his school in Arizona.
Mr. Gesner turned him down, looking to develop his own style while apprenticing under an uncle in Santa Barbara who connected him with carpenters and stonemasons, craftsmen who taught him the fundamentals of construction.
He designed an adobe home for his parents in Los Angeles, and in 1954 completed one of his first major commissions, a Hollywood bachelor pad for swimwear executive Fred Cole. Loosely inspired by traditional Polynesian huts, the home featured a steep roof design, bamboo curtains and a triangle-shaped swimming pool with a gas jet that sent flames shooting into the air. “In terms of notoriety,” Mr. Gesner said of the project, “it made my name well known.”
Mr. Gesner’s marriages to Audrey Hawthorne, Patty Townsend and Pat Alexander ended in divorce. In 1968, he attended a reception honoring one of his former high school classmates, actress Nan Martin, who was living in New York City and had a son, Casey Dolan, from a previous marriage. She later recalled that Mr. Gesner locked eyes with her from across the room and declared, “I have been waiting for you all my life.”
She soon packed her bags and moved in with him in California, where they married in 1969. Mr. Gesner built them a new home, the Sandcastle, which featured a large brick fireplace designed to reflect sound, so that Martin could give readings from the hearth. She died in 2010.
In addition to his stepson, of Port Townsend, Wash., survivors include a daughter from his first marriage, Tara Tanzer-Cartwright of Proctorsville, Vt.; a son from his third marriage, Jason Gesner of Berthoud, Colo.; a son from his fourth marriage, Zen Gesner of Malibu; and five grandchildren.
Mr. Gesner continued working into his 90s, developing a new windmill design and an eco-friendly structure called the Autonomous Tent, which is intended to endure heavy snows and high winds. He said he had no interest in retiring.
“I’m looking for a way to be reborn, you know, physically,” he told Vanity Fair in 2007, at age 82. “My father, he was fabulous. When he was dying, he was in his 80s. He’d had a massive heart attack, and I was there at his side, and he said to me, ‘Harry … I can’t wait for the next experience.’ That says it all.”