(CNN)Forrest Fenn, whose 10-year treasure hunt inspired thousands of people to explore out West, has died, police confirmed to CNN. He was 90.
Fenn died of apparent natural causes at his home in New Mexico, Santa Fe Police Deputy Chief Ben Valdez said.
Fenn was an art and antiquities collector and Southwestern raconteur best known for hiding a treasure chest somewhere in the Rocky Mountains. He published cryptic clues 10 years ago in his autobiography, "The Thrill of the Chase," and set off a treasure hunting phenomenon.
He estimated over 350,000 people went looking for the chest along the mountainous terrain. Some people quit their jobs and devoted their days to searching for it, and a few died during their search.
Skeptics believed his treasure hunt to be a hoax until June, when Fenn announced an anonymous adventurer had finally found the bounty. Fenn shared photos to prove the treasure was real all along -- a silver chest teemed with gold, jewelry and other artifacts, believed to total over $1 million.
He held onto his treasure hunt's secrets until the very end. He never revealed the exact location of where he'd placed the treasure, and he kept the finder's identity private.
Fenn lived most of his life in Santa Fe, a town, he wrote, populated by "many characters who are attracted to it." He proudly identified as one of those characters.
Treasure hunting wasn't his primary passion, at least for the first half of his life. Fenn blogged about being a fighter pilot in the Vietnam War and, in sharing one anecdote, questioned the morality of those who orchestrated the conflict. He also wrote online about his family, friends, and childhood trips to Yellowstone.
He ran an art gallery in Santa Fe, and his friends told the California Sunday Magazine in 2015 he didn't get into treasure hunting until the 1980s, when he was diagnosed with cancer.
Explorers who went searching for Fenn's treasure in the West thanked the late adventurer for the chase of a lifetime.
"He shared the beauty of the wilderness and that was the real prize," one user wrote.
Writer Porochista Khakpour shared images of her meetings with Fenn and the adventures he'd sparked her to take.
"Like many, I must say, thank you for the wild adventures," she wrote.