In 2010, a determined Diana Nyad, played by Annette Bening, sets out to achieve the unfulfilled dream of her youth: a 110-mile nonstop swim from Cuba to Florida, a challenge she had previously attempted but failed thirty years ago. Once a champion swimmer, Diana accomplished significant feats like traversing Capri to Naples, swimming 32 miles across Lake Ontario, and navigating 89 miles from the Bahamas to Florida, which was a record at that time. As she turns 60, she seeks a spectacular finale to her swimming career, one that eluded her previously.
Diana, in remarkable physical condition and eager for a new challenge, dives into her training by returning to a swimming pool after three decades, finding joy in the water once again. With excitement, she shares her ambitious plan to swim from Cuba to Florida with her best friend and former partner, Bonnie Stoll. Following a successful test run off the coast of Mexico, where Bonnie becomes convinced of Diana's potential, they both prepare for the daunting challenge ahead.
However, the frigid waters initially leave Diana apprehensive and ready to quit. It's only through Bonnie’s encouragement—drawing from expert opinions that suggest Diana's age could hinder her attempt—that she regains her determination. Despite facing public doubt regarding her age, Diana moves to Key West with Bonnie and brings in navigator John Bartlett, crucial for successfully traversing the challenging currents of the Gulf Stream.
Instead of using a shark cage, which Diana believes would compromise the swim's integrity, she chooses to employ a Shark Shield, a device designed to repel sharks. On April 20, 2011, Diana undertakes a 24-hour test swim in preparation for the main event. With Karly Rothenberg serving as the official captain, their team secures visas for Cuba, thus paving the way for the historic swim.
In August 2011, Diana embarks on her first attempt at the Florida Straits since 1978. With only 12 individuals in history having completed over 48 consecutive hours in the water, her endeavor is not just challenging but perilous. Unfortunately, adverse ocean currents force her to abort the swim after 42 hours, compounded by an allergic reaction to medication provided by the team medic.
When she attempts the swim again a month later, danger strikes in the form of box jellyfish. Despite sustaining stings, Diana insists on continuing her swim, even when she loses consciousness due to the venom. After her recovery in the hospital, Bonnie expresses her fears for Diana's safety and the risks her dream poses to the crew. Diana, undeterred, resolves to train for a year for one last shot at her dream.
Guided by a box jellyfish expert, she dons a specially designed protective suit for training—but the greater fears linger from her past, intertwined with flashbacks of abuse from her childhood swimming coach, Jack Nelson.
Come August 2012, Diana prepares for yet another attempt. Ignoring warnings of inclement weather, her desire to swim before the waters turn cold drives her forward. Amidst a thunderstorm, the situation grows tense as Bonnie and John plead for Diana to halt her mission, grappling with the threat of danger. After a heated argument, Bonnie steps away from training Diana, feeling that her support has come at the expense of her own dreams.
With time, Diana reaches out to John, seeking forgiveness, yet he declines to rejoin due to personal difficulties. After reconciling with Bonnie and reflecting on her past, their bond rekindles. John, realizing he has one last chance to support her, returns as navigator for Diana’s fifth attempt on August 31, 2013. This endeavor sees more favorable conditions and heightened tension, as the Shark Shield malfunctions and a shark approaches.
In a moment of exhaustion, as Diana hallucinates visions of the Yellow Brick Road and the Taj Mahal, Bonnie jumps in to motivate her to continue. On September 2, Diana triumphantly reaches the shores of Key West, met with jubilant crowds. In her speech to the press, she emphasizes three powerful messages: > "One, never, ever give up. Two, you're never too old to chase your dreams. And three, it may look like a solitary sport...but it takes a team."
