Intermittent showers sweep down from the blue-slate sky as the mail boat churns across the Chesapeake Bay. There is nothing around us, except for the occasional buoy bobbing defiantly in the white-tipped chop. The insistent growl of the motor makes conversation with the other two passengers nearly impossible, so I stare out the rain-splattered window into the foggy oblivion.

Our destination is Smith Island, a small chain of marshy, low-slung isles with three small communities spread across them. There's Ewell, the largest town and de facto capital; Rhode's Point, oftentimes referred to as Rogue's Point by islanders; and Tylerton, which is alternately known as Drum Point. The only inhabited offshore islands in Maryland, they are home to a small community of watermen and their families.

After settling in Jamestown, Virginia, Captain John Smith charted the Chesapeake Bay in the early 17th century; during those explorations, he dubbed a string of bay islands the Russell Isles. Later that century, Jamestown's own Henry Smith was granted 1,000 acres of this land, and the area's islands became known as Smith Island. Largely composed of salt marshes, it was used for generations as a place for livestock grazing; since the late 17th century, the locals have made a living by fishing for blue crabs in the summer months and oystering during the winter. But as strict fishing regulations, intended to bolster crab populations, continue to limit how many can be caught, and as cheaper Asian alternatives flood the shellfish market, locals are watching their longtime livelihood slip away.

The shift has led to a steep population decline as young islanders and families unable to support themselves have moved over to the mainland. According to the 2010 census, only 276 people now call the islands their home, down from a historic high of approximately 900 people a century ago. It is an aging population: More than 60 percent of islanders are over 50, while fewer than 10 percent have reached their 18th birthday.

The population isn't the only thing breaking down: The islands themselves are slowly slipping below the water as erosion devours a shoreline that never rises higher than four feet. According to the US Army Corps of Engineers, Smith Island has lost more than 3,300 acres of wetlands in the past 150 years. Though the agency is currently engaged in several projects that aim to protect and restore the remaining land, it may not be enough to save this fragile ecosystem.

"With the continuing rise of sea level, erosion is a fact of life on Smith Island," says Jeff Halka, director of the Maryland Geological Survey. "If you look at the history of the bay, there have been any number of islands—Holland Island, James Island, Poplar Island—that were inhabited with substantial communities, and now they're gone or virtually gone." It seems Smith Island's demise isn't so much a question of if, but when.

About halfway through the 45-minute trip by boat, Smith Island rises out of the mist like a submerged lost world breaking to the surface. At first all that can be seen are the tops of the trees waving in the wind, but soon the church steeple comes into view, followed by the modest one- and two-story homes that line the waterfront. Pulling up to the dock in Ewell, I am immediately swarmed by a black cloud of mosquitoes, gnats, and greenheads. "Lots of moisture and no wind," captain Otis Ray Taylor explains as I swat at the dive-bombers and frantically root around for my bottle of Off.

As soon as my skin is glistening with bug repellent and granted a reprieve from the bloodthirsty insects, I can appreciate these new surroundings. Birdsong brightens up the murky May day, providing a cheery soundtrack to the scene. The road to the town extends in front of me, while the shoreline next to me boasts several whitewashed rectangular shanties where watermen work.

That's where I find Mark Kitching, a lifelong crabber with soft eyes and roughened hands who has been working on the water for well over a quarter century. He is dividing his catch into two main categories: soft crabs that are ready to eat, and "reelers," which are about to shed their shells and become soft crabs. The former are neatly packed into waxed cardboard boxes to be sent over to the mainland, where they can fetch $25 to $30 a dozen. The latter are put into aerated tanks and monitored until the metamorphosis makes them market-ready.

Kitching's speech shows off the local drawl, which some linguists have dubbed Elizabethan, but which comes across more like a slightly twangy Southern accent. "This is probably the end," he tells me when I ask him where he sees the local crabbing industry going in the next decade. "There's nobody coming up after me."

Not far away, Janet Evans teaches first through seventh grades at the on-island school, which now has only eight students enrolled. Despite the declining ranks, Evans's warm classroom is crammed full of art projects in progress, a colorful jumble of toys, and pictures of all the American presidents. An alphabetical list of her students runs down the door of a cabinet. When I ask Evans if she thinks any of them will end up living on the island, she doesn't say anything, just shakes her head while pursing her lips.

She doesn't stay quiet for long. Soon she's talking about the precipitous decline of Smith Island. "It used to be that when the guys graduated—if they went to high school at all—they got their boat and went to work," she explains. "They married their sweetheart, settled down, and started a family. Now very few people want their children to stay here. When you keep pushing that, you can't expect the population to stay the same." Taking a deep breath, she finishes. "I hate to say it, but there's really no hope. I always thought that eventually, down the line, [the island's people] would see a situation like this; I just never expected it in my lifetime."

Janet Tyler, the manager of the Smith Island Cultural Center and a 13th-generation islander, echoes that sentiment. "We're in crisis mode with losing our people," she says, her eyes glistening with emotion. "Because there's no younger ones having families to generate people from. It's getting scary here." All around Tyler are reminders of the island's vibrant past. Hanging from the ceiling are pieces of traditional fishing equipment—a crab pot, an oyster dredge, a sculling oar—while an original crabbing skiff built in 1919 sits at the center of the small museum. And there is a corner devoted to Smith Island's culinary traditions, which show no sign of dying out.

Down a winding road from the cultural center, the Smith Island Baking Company occupies a building that was once a general store and the original post office. The bakery produces only Smith Island Layer Cake, the isle's most enduring contribution to regional cuisine. Made with anywhere from 8 to more than 12 thin layers of yellow cake and frosted with cooked fudge icing, it was officially designated Maryland's state dessert in 2008.

There are several stories about the cake's origins. Manager Kristen Smith's favorite version centers on watermen who would go out oystering in the winters following the Civil War. "Their wives would send them with provisions, and they found that a more traditional thicker layered cake with only two or three levels got stale quicker," she says. "The thinner layers and the cooked fudge icing kept it fresher for longer."

Today Smith and four women in baseball caps and yellow-striped aprons mix batter, fill pans, and oversee the ovens to turn out an average of 40 cakes a day, though that number can quadruple or quintuple during the holiday season, when orders are highest. They've shipped them out to all 50 states and seven countries. Taking a bite, I understand why this decadent dessert has earned international acclaim. The cake is buttery and moist, while the rich frosting offers up a deep cocoa flavor.

For dinner that night, I enjoy another local favorite at Susan's on Smith Island, the bed and breakfast where I'm staying. Proprietor Susan Evans prepares crab cakes—the main body of the Maryland blue crab simply broiled, with a hint of Old Bay. The meat is sweet, soft, and succulent.

I fall asleep to the sound of rain and wind lashing against the window of my cozy waterfront bedroom. When I wake up, the skies are picture-perfect blue and the sun is shining brightly, though a strong breeze is still moving sharp ripples across the bay.

Soon I am in the back of a powerboat heading over to the nearby Martin National Wildlife Refuge, an ornithologist's Shangri-la that sprawls across more than 4,500 acres. Numerous varieties of ducks, geese, and swan call the preserve home, though it's not uncommon to see birds of prey like bald eagles and the endangered peregrine falcon. On one spit of land tufted with small shrubs and a blanket of verdant marsh grass, there's a pelican breeding ground. A number of the birds stoically sit on nests carefully woven out of dried grasses, their beaks tucked down against their long necks, while others dip and dive in the sky above them.

"It's a paradise for waterbirds," says Wayne Bell, past president of the Maryland Ornithological Society. "During fall migration, the islands form nice stepping stones for birds that have to cross the bay coming down the Delmarva Peninsula."

Despite the fact that thousands of birds use it as a rest stop or a nesting place, it's not overrun by binocular-wielding nature tourists. "It's not promoted or very accessible," Bell says. "So that doesn't make it a mecca for birdwatchers, but a mecca for birds instead."

Continuing onward, we stop in at Tylerton. It's the home of the Smith Island Crab Co-op, where the crustaceans are cleaned and shelled by hand. I meet up with Robin Bradshaw, one of the few local women who still make a living doing this grueling work—although she supplements the oftentimes meager income by mowing lawns and cleaning the local Methodist church. She is wearing a well-worn navy blue shirt with USA bedazzled at the center, and burgundy sweatpants; her shoulder-length, streaked brown hair is pulled back into a rough ponytail.

The co-op's sun-battered sign out front is a reminder of better times. Only three women work here now, down from a high of 15 when it opened in 1996. "Some have moved away, some have died, and some have gone back to the way they used to pick by doing it at home," she explains. Bradshaw and her fellow pickers used to produce about 20,000 pounds annually; now they're lucky if they hit 8,000 pounds. She doesn't envision anyone in the younger generations carrying on this tradition. "My daughter is more anxious to move than to stay," she says with a resigned shrug. "This is a confined place. You've got to want to be here."

As I was shaking hands goodbye with waterman Mark Kitching the day before, he had echoed Bradshaw's bleak outlook. "None of the young guys around here are getting into the business," he says. "You're seeing the last of the Smith Island watermen." Obligations call back on the mainland, and I depart this faded idyll of Chesapeake life. Heading home across the Bay, I watch Smith Island recede into the distance. Finally, the sea and the sky swallow it up, as if nothing was ever there.

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