Roman Dial, a professor of biology and mathematics by profession, is a legendary Alaskan explorer. He’s competed in winter competitions across the state and climbed some of its highest peaks. He wrote the standard guide to packrafting — using a small, inflatable boat that can fit in a backpack to cross the raging rivers of Alaska’s interior and far north, where bridges are nearly nonexistent.

In 2014, Dial’s son Cody went missing while traveling in the jungles of Central America. Roman Dial and his wife, Peggy, hadn’t heard from Cody for two weeks before they began to really worry, and worry hard. “Shock washed over me. Then guilt,” Dial writes in his memoir, “The Adventurer’s Son.” “Guilt . . . that I hadn’t given him the attention he deserved. That, maybe, like Peggy pointed out in nearly every argument, I spent too much time on my own trips, on my own interests.”

The day after reading what turned out to be his son’s final email, Dial landed in Costa Rica to search for him and, hopefully, save him. “The Adventurer’s Son” is his gripping, honest, raw account of that search. Dial’s writing is clear, straightforward, stolid, the sort of judicious, even tone one often finds in adventure memoirs, such as Alex Honnold’s “Alone on the Wall” or “The Calling,” by Barry Blanchard. Adventuring, after all, requires a cool head and steady heartbeat.

Dial would need every ounce of that steadiness for his lengthy search. He encountered bureaucratic stonewalling, indifferent police and a persistent rumor that Roman had fallen in with an unsavory character named Pata Lora. “ ‘He’s a really bad guy. A thief. Into drugs,’ ” Dial is told. The government of Costa Rica refused to grant Dial permission to enter Corcovado National Park, where access is heavily limited. Sen. Lisa Murkowski of Alaska and Gen. John Kelly, the onetime White House chief of staff, offered help, though it was limited.

Shirking the local police, Dial ventured into the park to conduct his own search. His guide was a local farmer suspected of murdering an American woman, but he knows the mountains of Corcovado better than anyone. Still, Dial did not find his son. Cody’s disappearance became the subject of much speculation. A National Geographic documentary, “Missing Dial,” aired in the spring of 2016, positing the idea — floated by Roman Dial himself — that Cody was murdered.

Cody Dial’s remains were discovered on May of 2016; he had been killed by a falling tree in the jungle. Dial’s response to the confirmation of Cody’s death was mixed. He was torn, he writes, “between pain and relief. Relief, because it seemed the ordeal of searching without knowing might be over. Pain, because it would mean, once and for all, that our son was dead.”

Despite the dark revelations at the end of the book, its early sections are a celebration of outdoor life. They recount glorious explorations of Alaska’s high alpine peaks, winter races across Alaska’s wilderness, the story of how he met his wife, and his research in the tropics. But most beguiling is Chapter 8, which details how Dial took Cody, then 6, on his first backcountry adventure, a 60-mile trek across a remote island in Alaska’s Aleutian chain. In these pages, Dial captures the magic of camping with a child — the joy of a kid’s simple yet probing questions, the games played to pass the time, the ecstatic amazement over the littlest things. It’s a chapter worth reading before taking a kid into the woods.

Dial’s two kids grew up romping the world. They would accompany him on research expeditions to Borneo, Bhutan, Australia and across Alaska. Cody inevitably grew into an adventurer himself. But Dial has doubts about the adventure-loving upbringing he provided his son: “Maybe we should have limited ourselves as parents to team sports, Chuck E. Cheeses, the local cineplex.” Dial writes. Later he adds: “I couldn’t shake the feeling that everything I had done with him in the wild had all been a mistake. . . . I might not have hurt the six-year-old boy then, but the suffering of a twenty-seven-year-old man lost and broken in the jungle now felt like my fault.”

That’s a natural sentiment for a grieving father. I wish he wouldn’t judge himself too harshly. There’s the small (but empty) consolation that Cody died doing what he loved. But what Dial and his son had, for 27 years, was a lifetime of thrilling shared experiences — enough to fill a beautiful and tender book.

Timothy R. Smith, a former office manager of Book World, spent the summer 2019 season as a park ranger in Alaska.

the adventurer's son: A memoir

By Roman Dial

William Morrow. 368 pp. $28.99