There is some irony in the fact that it’s so difficult to put art dealer/outdoorsman/mystery man Forrest Fenn in a box. After all, the reason Fenn is mostly known around the world is a box. A $2 million lockbox to be precise, squirreled away in the Rocky Mountains somewhere between New Mexico and Canada. This treasure, hidden by Fenn sometime around 2010, has become nearly synonymous with the man himself. (He has no Wikipedia page, but his treasure does.) But who is this eccentric recluse, and why did he stash such an immense treasure for aspiring adventurers to discover?

At the sprightly age of 87, Fenn has spent his life wheeling and dealing in antiquities. He often is labeled an “art dealer,” but he’s much more. From a home base in Santa Fe, New Mexico, Fenn spent decades cultivating a posh clientele, everyone from Cher to Jackie Kennedy to John Wayne. He also traveled the world, armed with a deep dose of swashbuckling bravado, accumulating Egyptian relics and Georgia O’Keefe paintings and gold coins from shipwrecks. Peddling these glamorous goods to global glitterati is a large part of what built his legend.

A Texan by birth, Fenn arrived in Santa Fe after decades spent in the Air Force. He had never made it past high school, had no experience dealing in antiquities, but he rapidly started carving out his niche. Fenn would build his trade into a multimillion-dollar business, some say $6 million a year at its peak. His procurement methods always bore a whiff of mystery, but when you’ve got celebs like Steven Spielberg and Steve Martin stopping by your gallery, you earn the right to indulge in a little secrecy.

Fenn’s life dazzles those who observe him. He lovingly cares for his pet alligator, Beowulf. His favorite place to explore is the Sahara Desert. One time, he stumbled on a sunken treasure on a swim off the coast of Libya. He survived his fighter plane getting shot down over Laos. In fact, his life’s exploits are so extraordinary that they were gussied up for a semi-fictional portrayal in the 1993 thriller, “The Codex.”

Fenn allegedly found his first artifact, a Native American arrowhead, when he was only 9 years old. He and his father used to wander the wilds of Central Texas, looking for whatever flotsam they could spot. This arrowhead would set him off on a lifetime treasure chase, from the volcanic ruins of Pompeii to the desert caves of Arizona. In fact, his autobiography, released in 2010, was aptly titled “The Thrill of the Chase.”

Now, about that book. Fenn’s original plan to hide his treasure was hatched while suffering from a near-fatal bout of cancer roughly three decades ago. He didn’t think he would pull through, so the treasure would be his legacy. Fenn started looking around for a writer to pen his biography; within its pages would be the clues to finding the treasure. An important caveat — Fenn planned to lay down next to the treasure and die. Whoever found the priceless artifacts would also get Fenn’s skeleton in the bargain.

But Fenn survived. His cancer treatments worked, and he more or less returned to full health. He already had procured an ornate bronze lockbox to stash the treasure, though, and his mission never disappeared. Fenn spent years filling the box with a dazzling assortment of coins and gold nuggets, sapphires and Chinese jade. By the time the box was full, it weighed around 42 pounds; Fenn lugged it into the Rockies on a solo hiding journey. Then, “The Thrill of the Chase” was published, and amateur adventurers have been driving themselves mad ever since.

Fenn’s prose poetry is subject to a vast array of interpretation. The lines are just vague enough to allude to multiple locales; working through Fenn’s puzzle is a complicated task. He will occasionally step in and give direct guidance to his hapless followers, but it’s typically ensconced in a further riddle. As of yet, no one has found success, though there has been a handful of supposed near misses. (Sorry, Tom.)

But the collective frustration of all these seekers just serves to elevate Fenn’s legendary status. Dedicated true believers hold an annual “Fennboree,” while others spend hours logging on to Fenn message boards, dissecting the particularities of each clue. In the “Thrill of the Chase,” Fenn speaks to his devoted treasure seekers, hoping they have “as much fun finding it as I have had all these years collecting it.”