Robert Macfarlane has published five masterful books about walking and beautiful natural places. He seems to metabolize landscape into lyrics as he walks: “Follow the stream bed through gorse and bracken, setting fieldfares flaring,” he writes in his newest, Underland: A Deep Time Journey ($28, W.W. Norton), which takes his descriptive power below ground. At first this seems like something of a waste: there are no swallows skimming, no leaves shimmying to dapple the light. But this book explores more than his physical surroundings. “Seen in deep time, stone folds as strata, gouts as lava, floats as plates, shifts as shingle,” he writes. “Down here, too, the boundaries between life and not-life are less clear.”
He comes to identify the three main uses humans have for the underground: burying treasured things, hiding gruesome things, and extracting precious things. He visits examples of each, bringing readers to burial caves beneath an English hillside, a mine that extends under the ocean, and a mile-deep laboratory where physicists try to detect the subtle traces of dark matter. And he gives each cavern and tunnel the same scholarly, poetic treatment as the prettier things above ground.
In Slovenia he explores a “starless river,” as he calls the subterranean Timavo, where water has carved a porous network of caves and sinkholes through limestone and dolomite. Macfarlane climbs down into a chamber where the Timavo runs, guided by an old man who lights up a tobacco pipe as soon as the pair reach the dark, loud cave. They see dunes of soft black sand flecked with gold, dangling stalactites, an underground cliff that drops to the river, where unknown white forms move in black water. “The sounds of this starless river is like none I have ever heard. It has volume. Its volume has hollowness. Each sound has its echo, and each echo its interior,” Macfarlane writes. When the two emerge, back into the bright upper world, a friend tells Macfarlane he looks like he has just returned from another planet.
In each location, Macfarlane travels with at least one expert, and though he’s a seasoned hiker and mountain climber, he easily slips into the role of novice, learning the special techniques for maneuvering around these secret places. These relationships give the whole book a mythological feeling—a series of amiable Charons guiding our narrator across so many Rivers Styx. Underneath Paris, a young woman named Lina guides him through a network of man-made passages and chambers, never even pausing at the complicated junctions, moving as if she is carrying a map of the shadow city in her head. In a forest at the edge of London, a plant scientist named Merlin teaches him about the underground network of fungi that allows trees to share resources and information, and when night falls, the pair host a firelit sing-along, with friends appearing out of the trees to join them.
These moments of primal togetherness—Macfarlane’s guides often sing as they navigate treacherous places—are necessary ballasts that buoy both explorers against the constant specters of death. Early in the book, Macfarlane discusses the death of Neil Moss, a 20-year-old who died in a caving accident in England in 1959. Trapped in a narrow passageway, Moss’s own breath filled the shaft with carbon dioxide; several rescue attempts failed to save him before he suffocated. The young man’s father asked that the tunnel be sealed with cement so that nobody would put themselves at risk trying to recover his body. Macfarlane himself is aware that things can go (farther) south quickly in many of the places he visits. Some of the people operating within the extremity of the underground are there for work (scientists, miners) or for exploration (the woman clambering through secret passages beneath Paris) but in each is something of the pure thrill-seeker, whose lust for beauty or adrenaline has a shadow self that sometimes looks like a death wish.
Macfarlane calls this hunger for oblivion thanatos, after the Freudian term for death drive and the Greek god of nonviolent death. He articulates it as a part of the experience, not to be picked apart with armchair psychology or otherwise explained away. Diving in a flooded labyrinth beneath Budapest, Hungary, he opens his eyes and sees a dark, smooth tunnel. “Just as standing on the edge of a tower one feels drawn to fall, so I experienced a powerful longing to swim into the mouth and on, until my air ran beautifully out,” he writes. These moments are sprinkled sparingly but memorably throughout the stories—and the extremes of beauty and risk memorably intersect when Macfarlane is dangled deep into a radiant blue shaft inside a melting glacier, where the relationship between time and matter click into place.
The final location Macfarlane visits, a tomb for spent nuclear waste, in Finland, is eerie: gray and snowy, with a broken-down mechanical Einstein figurine and a purpose that forces visitors to try to grasp the vastness of radiological time. When the experts were designing a different radioactive sarcophagus, they suggested several types of “hostile architecture”—spikes, blocks, panels of granite with solar heating making them uncomfortably hot—to signal to people from the distant future, a hundred thousand years from now, that they should not investigate the site, should turn back and carry on elsewhere.
It seems wise that those designing the Finland site decided to let it simply become invisible. Cast your mind into the distant future, almost further than it can go, and imagine someone encountering a strange solar-heated disc or inexplicably forbidding javelin spikes. You don’t know much about how they might react—but if you recall Macfarlane untethering himself again and again in plummeting blackness or wedging himself under crushing stone, you know that, if they’re anything like us, whoever might be walking the earth in that distant future would not be able to stay away.