Deep in the Amazon jungle, magnificent rocky tabletop towers rise abruptly from the foliage, often cloaked in thick clouds. They're called "tepuis" ("house of the gods"), and their plateaus, or mesas, are completely isolated from the forest below. That makes them a tantalizing potential source for exotic new species. National Geographic is marking Earth Day with the release of a new documentary, The Last Tepui, featuring renowned biologist Bruce Means teaming up with elite climber Alex Honnold and a veteran NatGeo team to become the first people to summit one of these remote structures.

(Some spoilers below.)

Anyone who has seen the Oscar-winning 2018 documentary Free Solo will be familiar with Honnold. He emerged seemingly out of nowhere in 2007 with a free solo climb of Astroman and the Rostrum in Yosemite National Park and soon became a dominant force in climbing. Free Solo documented Honnold's quest to become the first to complete a free solo climb of El Capitan—not without controversy, given the very real risk of Honnold dying in the attempt. (Spoiler alert: He survived, completing the climb in 3 hours and 56 minutes.)

Means is less of a household name, but he is very much a giant in the biological sciences, having spent much of his storied career hunting for new species all over the world. Means had been on 33 expeditions to this tepui-rich region, but he had never managed to reach the top of one, given the challenge of climbing what NatGeo explorer and expedition leader Mark Synott (Lost on Everest) describes as "crazy towers in the jungle." This expedition would be a "first ascent" for one tepui in particular, as well as what would likely be the 80-year-old Means' last trip to the jungle.

Like the Galapagos Islands, these 60 tepuis (sometimes called "islands in the sky") are rich in biodiversity, with many plants and animals not found anywhere else in the world. Most are made of sheer blocks of Precambrian quartz arenite sandstone, remnants of a large sandstone plateau that once covered the granite floor of this region. One of the most famous is Mount Roraima (aka Roraima Tepui)—an inspiration for Arthur Conan Doyle's 1912 novel The Lost World, about the discovery of a stunning prehistoric world thriving in isolation on top of the tepui.

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Sinkholes sometimes form on the mesas, becoming as large as 1,000 feet in diameter and 1,000 feet deep. Ecologically, they are "islands within islands" and boast many species unique to that particularly sinkhole. So tepuis are hot spots of biodiversity. But even getting to the base of these structures can pose a major challenge, as the NatGeo team in The Last Tepui discovered.

Directed by Taylor Rees, the documentary follows Means, Honnold, Synott, and the rest of the crew as they hike through the dense vegetation of the jungle, with their guides hacking through the foliage to blaze a trail. The climbing sequence is genuinely suspenseful, and Honnold's mastery is on full display. The documentary features the kind of stunning panoramic views one would expect from National Geographic, and the climbing team even managed to conduct an interview with Good Morning America from their precarious Ledge Camp—all thanks to the wonders of 21st-century technology.

All that hardship and nail-biting suspense paid off scientifically: DNA analysis confirmed six new species among the specimens collected during the trip. Perhaps the best part of the documentary is Means himself, whose love for science and the region is palpable throughout. "This is my Shangri-La," he tells the camera while wading through a shallow river. "I'll be leaving the planet sometime, and I'll miss it."

Ars sat down with Honnold and Rees to learn more.