Phil Arnot, shown here during one of his countless excursions, looks back on his life of adventuring. “I can’t tell you where I went shopping yesterday, but I can tell you every step you take in climbing Denali,” he said. “I can remember anything that had an emotional attachment. And I had a lot of those.”   Courtesy of Phil Arnot

Phil Arnot said he’d start this story with the nightmares he had as a 3-year-old, when bat-like creatures fluttered out of the closet of his bedroom on 14th Avenue in San Francisco. Hovering above him in succession, they tormented the future Air Force pilot.

Now 93, the author and adventurer meaningfully replays those dreams. “Fear is a prerequisite of courage,” he said. “One night I turned the tables on them and I took control of my dream. This was 90 years ago, but I remember it vividly: opening the closet door where these monsters were and blindly charging. They took off. I was afraid, but I went ahead.”

For the longtime Lagunitas resident, courage is the most important human attribute. It would reappear when he piloted his B-17 Flying Fortress in 21 bombing missions during the latter half of World War II and again, in 1986, when he elected to return his war medals in protest of his country’s foreign policy in Nicaragua. And it was present throughout his countless treks into the North American wilderness, from the peak of Denali to the depths of the Yosemite Valley.

As he continues to bulldoze through his 90s, full of spry energy and collected wit, Mr. Arnot reflects back on a life he said was guided both by luck and fate. He speaks deliberately and recalls dates so rapidly it’s as though he’s reading them off of an eyechart.

A documentary on his life thus far (its subtitle reads “The First Hundred Years”) is nearing completion, and he has a large family gathering to finish planning for the day after Christmas. But when a waitress at the Two Bird Café last week asked Mr. Arnot what he really desires, he admitted that it’s to be “20 years younger—can you help with that?”

She laughed, and he grinned. Today, he’ll settle for a sundae. 

Mr. Arnot was born two minutes past midnight on July 15, 1924 in San Francisco. His father, an obstetrician, delivered over 10,000 babies and his mother was a nurse who encouraged his adventurous spirit, allowing him to visit his grandmother in Lagunitas on his own as a child. He claims he took his first hike at age 2, exploring the unspoiled poppy fields that surrounded his grandma’s rustic cabin. 

He enrolled in the University of California, Berkeley for $25 but the looming world war drew him to enlist. He chose the Army Air Corps because of the possibility of later becoming a commercial airline pilot. He flew through his training and graduated a year later with a uniform decorated with military feats. He said being an officer and pilot at such a young age made him self-conscious, but he quickly found himself in Europe, co-piloting a bomber in the Eighth Air Force in 1944.

The Eighth Air Force during World War II is remembered for its bravery and devastating losses. The British had decided not to bomb during the day, leaving the slot open for the Americans, who had just joined the campaign. It’s been said that there was a much greater risk of being killed, wounded or captured flying in the Eighth Air Force than if one was stationed on the front lines.

Mr. Arnot said he knew a plane had gone down if a friend was absent at dinner. And though he recognizes a person’s right to believe in some “cosmic guiding hand,” he himself became a student of fate during the treacherous war. 

Not long into his service, a seat on a bombing mission opened up. Stan Burns from Sacramento had a cold and the flight surgeon let him sit it out. Mr. Arnot was set to replace him but, at the last-minute, Mr. Burns changed his mind and boarded the plane. 

A few hours later, the B-17 was shot down, killing all but three on board. 

“That’s just sure fate,” Mr. Arnot said. “I just think it’s luck and fate.”

After the war, he photographed parts of Europe and northwest Africa to update military maps, and his photography grew into a hobby. He also returned to Cal and earned a degree in political science in 1950. 

The next year he began his first career as an international relations and U.S. history teacher for a high school in Belmont. Sometimes, after returning from weekend hiking trips, he let his students spend the entire class period inquiring about his experiences in the outdoors. 

Mr. Arnot married in 1951 and divorced in 1970. He has three children: fraternal twins Bruce and Cindy and his youngest daughter, Susan.

In 1979, Mr. Arnot retired from teaching and moved to his grandmother’s cabin in Lagunitas. He turned his attention to activism, in particular the Nicaraguan conflict. He visited the war-torn county in 1984 and produced a photo collage that he used to show at schools. Eventually he raised $50,000 for medicine and a Jeep to send to the country. 

Two years later, he marched into an Army recruitment center on Fourth Street in San Rafael with his military medals in hand and a message for then-Secretary of Defense Casper Weinberger. He was disgusted with the U.S. policy in Central America and reclaimed his honor by disposing of his decorations.  

Mr. Arnot’s second career was in the wilderness, either guiding hikes or writing books about it. In the mid-1990s, while guiding a backpacking trip, he met a woman named Sandy; they’ve been together ever since. “I always wanted to be with a woman who was beautiful and loved the wilderness like I did,” he said. Between them, they’ve spent over 700 days in the wilderness.

Mr. Arnot’s maxim is that “human beings everywhere have an innate affinity, even a need, to be with wilderness. Not just once or twice, but on an ongoing basis.” His backcountry gospel caught the attention of a publishing company that asked if he’d write a book on Point Reyes in the late 1980s.

“My initial reaction was who would want to read a book on Point Reyes?” he said. But he went on to publish “Point Reyes–Secret Places and Magic Moments” in 1987.  The book is remembered fondly for its designation of various sites: Elephant Rock Overlook and the secret cave near Limantour Beach, in particular. “My travel guide was an attempt to describe beautiful things to see and not be a sterile, left turn, right turn book,” he said. “I had seen some unusual places at certain seasons of the year or days of the week.”

But a section on the unknown coast between Kehoe and McClure Beaches led to a dispute with the park service. Even though Mr. Arnot had outlined specific instructions for accessing these off-the-beaten-path spots, noting the shifting timetable and the need to wait for low tides, readers would still find themselves caught between a rock and a wave. 

“A couple who hadn’t read it carefully got cut off and tried to climb a cliff,” he said. “They had to be rescued by helicopter. And as I remember, the park service pulled the book from the bookstore. I was mad as hell. When a climber is killed in Yosemite, you don’t pull a climbers guide.”

John Dell’Osso, a spokesman for the seashore, said the incident wasn’t Mr. Arnot’s fault, but the park service did ask him to add a statement in updated versions of the book to remind readers to approach the tides with serious consideration. After he did, the seashore began selling the book again, which Mr. Dell’Osso said had a real impact on adventurers.

“He is literally a fountain of knowledge and has never had any malintent in any way, shape or form,” Mr. Dell’Osso said. “Phil has helped educate a lot of people in the greater Bay Area about wonderful hikes and how to enjoy them safely.”

Though he has enough years behind him to remember when the speed limit on Highway 101 was only 45 m.p.h., Mr. Arnot is far from spending his days creaking back and forth on a rocking chair. His goal is to reach 110 years (he briskly knocks twice on a wooden table). 

He’s shown a retrospective of his photography in San Geronimo in 2003 and opposed Steve Kinsey’s race for district supervisor because he believed his campaign was financially backed by developers. (“I’ve since mellowed,” he said.) He’s been a member since 1979 of the Fairfax Health Club, where he regularly conducts an hour-long routine on the treadmill. 

Five years ago, a friend at the gym asked Mr. Arnot if he was familiar with the Legion of Honor, a French award that commemorates World War II soldiers. He hadn’t, and didn’t think much of it, but his daughter Cindy did. In 2012, he was presented with the award in San Francisco by French ambassador Romain Serman.

“Today, we are celebrating a hero whose courage and dedication contributed to saving our common values, justice and democracy,” Mr. Serman said during the ceremony.

Mr. Arnot was humbled by the award. Still, “The guys who really deserve it,” he said, “are buried in Normandy.”