San Nicolas is the most remote of California's Channel Islands, a wind-scoured platform of ancient volcanic rock rising from the Pacific roughly sixty miles southwest of Los Angeles. The Nicoleño people flourished here for millennia, seafaring traders who paddled canoes to exchange goods with the Chumash and Gabrielinos on the mainland. Archaeological sites scattered across the island suggest it may have served as a kind of gathering place for multiple tribes. The waters teemed with abalone, whale, fish, and sea otter, and the Nicoleños developed a distinctive stone tool tradition found nowhere else. By the time Spanish missionaries arrived in California, however, the population had dwindled. Disease, violence from Russian otter hunters, and forced relocations reduced the Nicoleños from a thriving community to fewer than twenty souls by 1835. When missionaries sent a ship to remove the survivors, they were carrying away not just people but the end of an eight-thousand-year human presence.

The woman the Spanish later named Juana Maria was roughly thirty years old when she leapt from that ship. Historical accounts long claimed she dove overboard to retrieve a baby left behind, though modern researchers have questioned nearly every facet of the accepted story. What remains certain is that she survived. For eighteen years she caught her own food, constructed shelters from materials at hand, and marked her time with notches on a stick. When sea otter hunter George Nidever finally found her in 1853, she was living in a structure partially framed with whale bones, her clothes fashioned from cormorant feathers stitched with sinew. Nidever described her as strong and active despite being around fifty years old, her face perpetually smiling. She could not communicate with any mainland tribe they brought to translate. Four words and two songs recorded from her suggest she spoke a Uto-Aztecan language, but its precise relationship to other California tongues remains a mystery. Seven weeks after reaching the mainland, Juana Maria died of dysentery. She was buried in an unmarked grave at Santa Barbara Mission.

The island Juana Maria once had to herself now belongs exclusively to the United States Navy. Since the 1930s, San Nicolas has served as a weapons testing range and support facility for Naval Base Ventura County. Rocket launches arc over waters where Nicoleño canoes once paddled. The Navy presence has paradoxically protected some of the island's natural character. Feral cats, introduced by officers before 1952, once devastated native wildlife including the endemic island fox and island night lizard. An eighteen-month eradication effort completed in 2012 removed the cats at a cost of three million dollars. Today the island supports three endemic land vertebrates found nowhere else on Earth: the island night lizard, a subspecies of deer mouse, and the San Nicolas island fox. More than ten species of snails exist only here. Giant coreopsis and coyote brush dominate the coastal bluff scrublands, and rare biological soil crusts carpet the windswept interior, harboring cyanobacteria species so unusual that several were only recently described by science.

San Nicolas is closed to the public. No ferries run here, no tours visit Juana Maria's cave or the archaeological sites that pepper the island's eroded slopes. Yet her story lives on in ways she could never have imagined. Scott O'Dell's Island of the Blue Dolphins, published in 1960, fictionalized her ordeal as the tale of a girl named Karana and has been read by millions of schoolchildren. In recent decades, researchers have worked to separate fact from legend, publishing evidence that Juana Maria may not have been entirely alone and that her people may not have fled at missionary urging. In 2012, archaeologists announced they had located the cave where she spent much of her solitary years. The Santa Barbara Museum of Natural History commissioned a historically accurate portrait, giving a face to a woman whose real name no one knows. The island itself endures as it always has: windswept, isolated, and deeply strange, a place where eight thousand years of human history ended with one woman's leap into the sea.