Photograph by Kim Keever for The New Yorker

I stared for a while at the placid face of Long Island Sound before I could make out Bren Smith’s farm. It was a warm, calm morning in September. Sixty buoys bobbed in rows like the capped heads of synchronized swimmers. It wasn’t until Smith cut the engine of his beat-up boat, Mookie, that I knew for sure we had arrived. The farm, a three-acre patch of sea off Stony Creek, Connecticut, starts six feet underwater and descends almost to the ocean floor. From the buoys hang ropes, and from the ropes hang broad, slippery blades of sugar kelp, which have the color and sheen of wet Kodak film.

At first, the local fishermen thought that Smith was growing some kind of marine hemp; that seemed cool. When they found out it was seaweed, they ribbed him relentlessly. Smith, in any case, prefers to call his produce “sea vegetables.” He also raises mussels, scallops, clams, and oysters in lantern nets shaped like accordions and stacked pyramids. He pulled up a lantern net full of twenty thousand black-and-orange scallops, two months old, the size of M&M’s. The net was covered in murky, greenish clumps of seaweed, crawling with sea squirts, little crabs, and translucent shrimp. “The farm is a reef for hundreds of species,” he said, cutting off a hank of seaweed—Gracilaria—for me to try. It crunched, filling my mouth with the taste of lobster juice. “This is what you want to see,” he said. “This is good, restorative ocean farming.”

Seaweed, which requires neither fresh water nor fertilizer, is one of the world’s most sustainable and nutritious crops. It absorbs dissolved nitrogen, phosphorous, and carbon dioxide directly from the sea—its footprint is negative—and proliferates at a terrific rate. Smith’s kelp can grow as much as three-quarters of an inch a day, maturing from pinhead to ten-foot plant in the course of a winter, between hurricane seasons. It is resilient, built to take a lashing, but if a storm wipes out the crop he can just start over. Every year, he harvests between thirty and sixty tons of it, about the same per-acre yield as a potato farmer. Plentiful, healthy, and virtuous, kelp is the culinary equivalent of an electric car. “You’re not just gaining nutrition, you’re also gaining absolution from guilt,” Mark Bomford, the director of the Yale Sustainable Food Program, says. “This is your get-out-of-anxiety-free card.”

As industrial land-based agriculture becomes increasingly untenable—environmentally destructive and at the same time vulnerable to drought and changing weather—we are being pushed out to sea. Smith says, “The question is, Are we going to do it right or wrong?” He calls his system, which uses the entire water column, a “3-D farm,” and he would like to see it become the dominant form of aquaculture. He would like to see kelp—a potential source of human food, biofuel, and animal feed—supplant crops like corn and soy. In October, his farm design, which he has made open-source, won a prize given by the Buckminster Fuller Institute for innovative solutions to urgent global problems. Not long before that, he was honored by Bill Clinton at the Clinton Global Initiative meeting in New York, where he showed up without realizing that he had a twelve-inch fillet knife in his backpack.

But Smith’s ambitions extend beyond reshaping an industry. In his vision, kelp farming can rehabilitate the ocean’s threatened ecosystems, mitigate the effects of climate change, and revive coastal economies. With thirty thousand dollars of start-up money and a boat, he figures, an out-of-work fisherman can make seventy thousand dollars a year. “There are no jobs on a dead planet,” he likes to say. Two years ago, he started GreenWave, a nonprofit through which he trains fishermen to be kelp farmers. Smith plans to form a twenty-five-farm co-operative revolving around a seafood hub near New Haven, with processing equipment, a seed bank and hatchery, value-added venders making kelp smoothies, and a Beyond Fish market, where the only fish available will be barramundi, fed on seaweed. In the often overwhelmingly grim conversation about ocean health—some scientists predict fishless oceans by 2050—Smith’s hopeful narrative is good for morale, promising that we can eat and thrive in an ever more populous and warming world. “It’s important to know that there’s a way to still sustainably work within the ocean,” May Boeve, the director of the climate-focussed advocacy group 350.org, says. “It’s not a lost cause.”

All Smith needs to do is to invent a new cuisine based on filter feeders and seaweed. He is starting with the East Coast offices of Google. “I use ocean vegetables at the center of the plate and garnish the plate with those restorative water-cleansing shellfish,” Michael Wurster, the culinary director, told me. “My users are conscious about what they eat, where it comes from, and how it was raised.” For others, though, there are some challenges. Sliminess is not a property that most Americans appreciate in food. “What is that disgusting oobleck?” was the comment that greeted the slick heap of kelp spaghetti I served to a preschooler not long ago. Howard Fischer, a hedge-fund manager who personally invests in regenerative agriculture and restricts himself to foods that meet those criteria, told me, “People who are eating with their minds first will be the early adopters, but there are no guarantees here.” When I asked Boeve about her taste for kelp, she said, “I need a little more time with it. I’m more of a bivalve person myself.”

The morning after taking me to the farm, Smith was back in Stony Creek to meet a fisherman he was recruiting to grow kelp for the co-op. Smith, who is five feet five, bald-headed, and bulk-shouldered, like the lobsters he spent his adolescence hauling from the sea in traps, was wearing dirty jeans, suspenders, and a blue T-shirt that said “Kelp Is the New Kale.” He was drinking water from an old whiskey bottle. He has epilepsy, triggered by two things he likes and one that he can’t avoid: alcohol, caffeine, and not getting enough sleep. Before he was a full-time farmer, he drove a lumber truck and sold pieces of the Coney Island boardwalk stencilled with obscure words like “petrichor” (the smell of rain on dry earth) and “limerence” (tingly infatuation) to tourists in Union Square. Once, while he was working at a table saw, a board flew in his face and knocked him out. He still has a scar running across the bridge of his nose. After the accident, he found that he had developed an allergy to shellfish. He has never learned to swim.

The fisherman, David Blaney, had driven down from Point Judith, Rhode Island, where his family has been farming and fishing the coast for three hundred years. His people used to fertilize their crops with seaweed, insulate their houses with it, and eat it in hard times. He is sixty-seven, white-bearded, taciturn; around his neck he wore the tooth of a mako shark that tried to kill him when he caught it while long-lining for tuna off the Grand Banks. In the course of his career, he said, he’d trawled for cod on huge boats known as Big Green Dump Trucks and, when the cod ran out, for swill like butterfish and whiting; then there was only squid to catch, then nothing much at all. “The past ten years, the way fishing’s been, I’ve branched out,” Blaney said, stepping onto Smith’s boat. “Marine survey, marine safety. But I’ve got nephews and kids myself who would like to go back to making a living from the sea.”