The education of MaVynee Betsch began with a fistful of five-dollar bills. Betsch grew up in a 22-room mansion in Jacksonville, Florida, and spent the 1930s and '40s immersed in the city's thriving African-American neighborhood. Her great-grandfather, Abraham Lincoln Lewis, had helped found the Afro-American Life Insurance Company—"Florida's first life insurance company, black or white," says Betsch—and it had become a bulwark of Jacksonville's black community. Lewis, meanwhile, had entered the record books as Florida's first African-American millionaire. Immensely proud of his race, and with an acute sense of social responsibility, Lewis would lecture his great-grandchildren: "Understand that everything you do makes a statement, whether it's your jewelry, your clothes, or your house," Betsch remembers. As she tells it, Lewis even went to the trouble of changing 20-dollar bills for 5s, preferring to do his business with the portrait of Lincoln rather than that of the hated Indian-fighter Andrew Jackson.

Now, at age 70, Betsch lives on Florida's Amelia Island, just shy of the Georgia border and less than an hour's drive from her childhood home. She follows her great-grandfather's guidance—though perhaps not quite as he intended. A gaunt six feet tall with plumb-line posture, she wears clothes that would outshine the plumage of a tropical bird and decorates her elegant neck with beads, stones, and seashells strung on fishing line. "See this dreadlock?" Betsch says a few moments after we meet in her breezy second-floor apartment. The winding gray mass of hair, draped over her arm, is impossible to miss—as thick and wide as a parka sleeve, it's a good seven feet long. Today, she says, it symbolizes an elephant's trunk. Other days it represents the curve of the Niger River, or the Gulf Stream. Whatever meaning she chooses, her coif provides an opening for a history lesson or an environmental or political diatribe.

"It's all hooked together—the hair, the clothes, the colors," Betsch says. "I wear orange lipstick because, baby, during the days of segregation, they couldn't even leave the ocean alone. They put an orange rope in the water, and one side said 'White,' the other side said 'Colored.' A rope! Out! in! the! ocean! Can you believe it?"

Even her name, pronounced "Ma-veen," requires a politically charged translation. Christened Marvyne, Betsch added an extra e for the environment, and dropped the r in the 1980s to protest the environmental policies of the Reagan administration. (Her friends now wonder when Betsch will become Etsch.) An inveterate performer, Betsch was trained as a singer at the Oberlin Conservatory in Ohio, where she graduated near the top of her class, and launched an operatic career in Europe. It's been nearly half a century since she played Madame Butterfly and Salome, but her voice can still swoop from a deep rumble to a piercing squeak, then explode into hoots and screams of laughter.

These days the main beneficiary of Betsch's unchecked energy is her home, the unincorporated community of American Beach on Amelia Island. Amid the narrow, 13-mile-long island's high-rise condominiums and gated developments stands the town—a quiet 120-acre jumble of cottages, cinder-block buildings, and jarringly new homes cradled by a 60-foot sand dune, the tallest on Florida's east coast. American Beach is a historical landmark and a relatively intact smidgen of coastal habitat—an unusual mix of culture and nature that Betsch is fiercely determined to protect.

American Beach was founded in 1935 by Betsch's great-grandfather. Born just two years after the Emancipation Proclamation, A. L. Lewis was all too aware of the legacy of slavery, and of the pain caused by segregation. A philanthropist as well as an entrepreneur, he decided to establish a resort for African Americans, a place for "recreation and relaxation without humiliation." Lewis's Afro-American Life Insurance Company, known as the Afro, purchased several adjoining tracts of beachfront land on Amelia Island and sold homesites to prominent black Floridians. Though there were a few other southern beaches that welcomed African Americans at the time, American Beach was one of a scant handful that offered lodging, restaurants, and entertainment—all the makings of a proper resort. In the decades that followed, the wealthy and the not so wealthy came to American Beach in droves. They traveled from all over the South, often venturing through rural counties sympathetic to the Ku Klux Klan. They packed Evans Rendezvous, a beachfront nightspot, where they danced to live performances by Ray Charles and Duke Ellington. "Oh, I can still feel the joy today," says Marsha Phelts, a local historian who grew up visiting American Beach. "You were with everyone you loved, your family, your buddies from church. You'd hop from one blanket to another, visiting pals here and pals there. It was fun, fun, fuuuun." American Beach was just one expression of black prosperity in the region. LaVilla, the Jacksonville neighborhood where Betsch grew up, was crowded with black-owned businesses and drew national musical acts to its theater. The Afro built an ultramodern glass-and-marble office building in 1956, a style later adopted by white-owned companies. "We walked around so proud," says Betsch. "We didn't have to ask white folks for anything!"

Ironically, one of the greatest victories of the civil rights era helped dismantle these accomplishments. With desegregation, blacks poured into white-owned businesses, but few whites visited black-owned establishments. In his 1998 book American Beach, journalist Russ Rymer describes one effect of this reform: "The whole economic skeleton of the black community, so painfully erected in the face of exclusion and injustice, collapsed as that exclusion was rescinded."

Betsch, drawn home from Europe by the call of family in the mid-1960s, found her childhood neighborhood—and her beloved beach—in decline. She settled in Jacksonville with her mother, who had bought a suburban house overlooking a marsh. And that view, Betsch says, was the beginning of her career as an environmentalist. "It was like something in my brain just went," she says, snapping her fingers. "There were herons; the ducks would come in November. I read every book about birds I could find. I went berserk."

After her mother and grandfather died in 1975, Betsch moved into her grandfather's house on American Beach. Amelia Island was thick with greenery: Twisting oak branches hung with Spanish moss shaded its narrow roads, and its forests were studded with pines, magnolias, and spiky saw palmetto. Betsch had some health problems and spent long days alone on the beach, convinced nature was curing her. The beach's butterflies particularly entranced her. "It was those colors—and flight for its own sake," she says.

So when Betsch contemplated her substantial inheritance, she thought not of yachts or trophy homes, but of insects. She read about an organization dedicated to their conservation, the Xerces Society, and wrote to its founder, butterfly expert Robert Michael Pyle. Over the next several years, she donated frequently to Xerces, paying for travel that helped researchers create the first International Union for the Conservation of Nature and Natural Resources "Red Data Book" for invertebrates—still the most comprehensive list of threatened invertebrate species. Betsch's contributions also fueled efforts to protect the world's largest butterfly, the Queen Alexandra's birdwing butterfly of Papua New Guinea.

Betsch sent Pyle hundreds of encouraging letters over the years, along with the occasional pot of honey or packet of medicinal herbs. "She has such a marvelous, contagious spirit," says Pyle. "I've known thousands of conservationists, but I don't know of anyone else more convinced of the rightness of their work."

Adopting her great-grandfather's tradition of philanthropy (but not his methodical business habits), Betsch became a life member of ten environmental organizations and at one point belonged to more than 50 groups, including the Sierra Club. "As soon as it came in the mail, I would join it," she says. She treasures a letter from Kenyan environmental activist and 2004 Nobel Peace Prize winner Wangari Maathai and an Audubon Society field guide to butterflies by Pyle, which carries her name on the dedication page. "Being black and in the South, I thought I was powerless here," she says. "Most of the causes I supported were far away."

Before long the money ran out. Way out. Betsch was forced to sell her grandfather's house, and for a time she even lived on a lawn chair on the beach. Her sister Johnnetta Cole, an anthropologist who's now president of Bennett College in North Carolina, gave her a small RV, providing Betsch with space to store her expanding collection of press clippings, books, magazines, and historical documents. Betsch gets by on a small stipend her sister sends each month, and she says, demurely, "We are limited now." But she won't admit to any regrets. In the opera, she points out, the rich hardly ever get to play the romantic lead.

In the face of her reduced circumstances, Betsch began calling herself the "Beach Lady" and focused on battles closer to home. In the early 1970s, mega-resort developers had discovered the charms of Amelia Island. And the residents of American Beach soon found themselves sandwiched between burgeoning luxury developments, their pocketbooks squeezed by rising property taxes. Land purchases by developers shrunk the town to about half its original size.

American Beach could easily have disappeared—but it didn't, thanks to Betsch and her allies. She won a battle for a buffer of intact land between American Beach and developments to the north. On the south end of Amelia Island, she helped protect an old bridge as a fishing pier. She and others also blocked developments on adjacent islands and successfully campaigned to add American Beach to the National Register of Historic Places. During these campaigns, she regaled county commissioners with speeches about "devil-opers," wrote letters, spoke to school groups, traveled to the state capital in Tallahassee to lobby and protest, and otherwise made herself impossible to ignore. "It's history and nature all wrapped together, baby," she says. When biologists came to Amelia Island in the 1990s to study the endangered right whale, they were so inspired by Betsch's persistence they named a whale after her. "Whale 1151—that's MaVynee—is known as a particularly rambunctious female," says biologist Chris Slay.

Despite—or maybe because of—her theatrical style, she attracted a diverse crew of allies, white and black, rich and poor. Several of her friends say, only half jokingly, "I just do what MaVynee tells me to." Phillip Scanlan, a former AT&T executive in New Jersey who retired to a gated community on Amelia Island five years ago, got to know Betsch when they were both active in the Florida Chapter of the Sierra Club. "When I came here, I knew nothing about this county," he says. "MaVynee was my coach."

Through it all, Betsch's renown grew. Her apartment—the successor to the RV—is lined with plastic milk crates, each filled with documents and labeled with her looping handwriting. Magazine and newspaper articles, many about Betsch herself, lie in drifts on nearly every horizontal surface, the text festooned with asterisks, double lines, and exclamation points. A small wooden billboard outside her apartment advertises "Black History Tours with the Beach Lady" and features her unmistakable silhouette.

Scanlan, who takes Betsch shopping about once a week, says, "When we walk into Wal-Mart, everyone starts waving and two cashiers want to wait on her. They say to me, 'Who are you?' and I say, 'Oh, I'm just the chauffeur.'" When Betsch and I visit her great-grandfather's mausoleum in Jacksonville, a young man driving by in a pickup waves, shouting, "Beach Lady!" across four lanes of traffic. Betsch smiles and shrugs. She has no idea who he is. Betsch's most memorable performance yet was undertaken on behalf of the dune locals call NaNa. Rising behind American Beach's homes like an amphitheater, NaNa is an imposing centuries-old reference point for mariners. It's also a part of local history. "You hear the stories," says Carol Alexander, executive director of an African-American theater and museum in Jacksonville. "People will say, 'Yeah, I got my first kiss up there on NaNa.' There's a life force about it."

In 1995, a developer purchased about 100 acres of the original American Beach property, including the dune. The undeveloped tract, unlike most of the rest of the town, had remained in the hands of the Afro-American Life Insurance Company. When the Afro hit hard times in the 1980s, it put the land up for sale. The Amelia Island Company, which had already built a 1,300-acre resort nearby, soon broke ground for Osprey Village, a retirement and golfing community, directly behind the dune. Though the company placed a conservation easement on most of the dune, Betsch and other residents didn't think that was enough. Betsch wrote repeatedly to the company's president, Jack Healan, and to state agencies, imploring them to cement protection for NaNa. "She just kept it out there constantly," says Alexander. "She knew that NaNa would be next."

But in 2002, Betsch underwent major surgery for colon cancer. That's when Alexander, searching for a way to honor Betsch's work and lift her spirits, called the company's president herself. Healan, who knew Alexander, was receptive to her ideas and eventually agreed to donate 8.5 acres to the National Park Service's Timucuan Ecological and Historic Preserve, a network of sites in the Jacksonville area. The problem was, adjusting the boundaries of a national park or preserve requires an act of Congress.

So began a new round of negotiations. Senator Bill Nelson (D) and Representative Ander Crenshaw (R), both of Florida, introduced congressional bills approving the addition. In May of last year, Alexander traveled to Washington, D.C., to speak to the Senate National Parks Subcommittee on behalf of the proposal. In October, President Bush signed the legislation, and NaNa officially became the property of the National Park Service.

At a ceremony in 2003, when Healan made his pledge to donate the land to the park, Betsch presented him with a signed photograph of herself. "You didn't have a chance," she teased. Thanks largely to Betsch and her wily activism, the natural and historical monuments of American Beach stand a good chance of survival. The Trust for Public Land recently purchased Evans Rendezvous and plans to turn over the shabby but still sturdy building to the county. After restoration, it could become a visitor center, an event venue, a small museum, or a combination of the three.

As president of the A. L. Lewis Historical Society, Alexander is now helping to plan a series of "family reunions," summer beach gatherings that will include the old and the young. "As long as we keep talking about it, American Beach will stay alive," she says. "Younger people will create a new culture there. They'll start to etch in the sand what it means to have this leisure area for themselves."

Though Betsch has defied all the expectations of her doctors, and was well enough to attend three gala birthday parties her friends threw for her last January, her health remains precarious. "MaVynee's at the point where she's saying"—and Alexander lowers and slows her voice to do a convincing imitation of Betsch's—"'Baby, I've done what I'm supposed to have done.' And she's absolutely right."

Michelle Nijhuis is a freelance writer living in western Colorado.