We're living in the golden age of documentary films. Thanks to the advent of inexpensive cameras and facile editing software, the number of skilled filmmakers who are reporting from the front lines of the essential stories of our time is truly remarkable. Which is why we've chosen to focus on the new: We've picked the 15 greatest adventure, investigative, and nature documentaries of the 21st century, while also giving nods to ten 20th-century classics that paved the way.

Guest editor David Holbrooke is the festival director of Mountainfilm in Telluride

Adventure
TRUE-LIFE EPICS
Riding Giants
There's a peculiar challenge to making a surf film: The action footage is so good, it's easy to get lazy with everything else. But director Stacy Peralta wasn't just trying to chronicle a surf quest. He wanted to explain the evolution of a sport. Peralta is the Ken Burns of boardsports (he directed 2002's skating history Dogtown and Z-Boys), and Giants, made in 2004, was his Baseball, with the brash pioneer Greg Noll and the modern master Laird Hamilton sparring for the role of Babe Ruth. Indeed, it's the surfers, not the surf, who make Riding Giants so much fun. Even as they describe the terror of wiping out at Maverick's, you can sense their smirks. They are crazy, clearly. But, by God, are they stoked!

Man on Wire
In 1974, French performance artist Philippe Petit and a team of riggers infiltrated the Twin Towers and strung a high wire between them, enabling Petit to spend 45 minutes performing 1,300 feet above Manhattan. History forgot about the Frenchman until 2008, when director James Marsh resurrected Petit's story in the Oscar-winning documentary Man on Wire. Combining actors' reenactments and interviews with all of the original players, the film explains just how the bohemians fooled the guards, strung the cable, and pulled off an amazingly illicit stunt in what's become haunted airspace.

Touching the Void
Joe Simpson and Simon Yates's 1985 escape from their first ascent of the west face of Peru's 20,853-foot Siula Grande became one of mountaineering's greatest epics with the publication of Simpson's 1988 memoir, Touching the Void. The 2003 documentary of the same name, by director Kevin Macdonald, masterfully re-creates both the feat and the disaster, which started when Simpson fell and smashed his tibia through his kneecap. Yates lowered his partner through a blizzard, then, when Simpson's weight began to drag both men off the mountain, cut the rope, sending a nearly unconscious Simpson on a free fall into a crevasse. Simpson's four-day crawl back to base camp redefined the limits of human endurance. "I just cried and cried," Simpson recalls in the film. "I thought I'd be tougher than that." Turns out he was.

Encounters at the End of the World
Only an obsessive like Werner Herzog could put reality on film, zoom in on the mystery, and create something that's more far out than any sci-fi. One of the most overlooked movies of the decade, 2008's Encounters was filmed at McMurdo, the U.S. research station on Antarctica peopled by "philosopher/forklift drivers" and other "linguists on a continent without languages." There are singing seals under the ice, microorganisms that haunt the daydreams of biologists, and, yes, penguins—but Herzog is only interested in the rogue members of that society that venture off in the wrong direction, for reasons nobody understands. It's a fitting metaphor for the humans who converge at the bottom of the planet, looking for new truths that may hold the keys to our survival.

Stranded
Alive, the 1993 Hollywood film starring Ethan Hawke, amped up the story of the 1972 plane crash that stranded an Uru­guayan rugby team in the Andes. ("Hey, I'll pay you for the pizza if you go and get it!" jokes one survivor, before they decide to eat the flesh of the dead.) Stranded: I've Come from a Plane that Crashed on the Mountains, Gonzalo Arijon's 2007 documentary, tells this story the proper way: with reverence. Arijon re-creates the plane crash, then gathers the 16 survivors and simply allows them to recount their ordeal. The result is haunting. Here's hero Nando Parrado, who eventually hiked out to find help: "Others saw it as a holy communion. That's fine. I wanted to see my father. To live."