Photo: Dana Mermaid

In the waters off Long Island, cameras captured a woman with flowing hair, a seashell bra—and a fish tail. The mermaid (or rather, the woman in the mermaid costume) was performing in documentary filmmaker Susan Rockefeller's Mission of Mermaids, a short film that combines a sweeping history of mermaid lore (from ancient Greece to the Disney era) with startling facts about the pollution and overfishing that threaten our seas. Rockefeller's decision to lend her project a dash of storytelling pizzazz was a strategic one. "We're inundated with statistics about global issues, and it gets overwhelming," she explains. "So I wanted to combine myth with science." The film—a sneak peek of which showed at Sundance this year—suggests ways to save our seas, from refusing plastic grocery bags to buying sustainable seafood. Recently, Rockefeller also designed a line of mermaid-inspired jewelry, available at susanrockefeller.com; a portion of each sale benefits the marine protection organization Oceana. When people compliment the pieces, Rockefeller leaps at the chance to share her enthusiasm. "You don't win people's hearts by preaching," she says. "They need to see your passion."