Madison Stewart is a 20-year-old Australian who has been diving alongside sharks since she was 12 and filming them underwater since she was 14. “Shark Girl,” her Smithsonian Channel documentary, will premier this weekend at the National Museum of Natural History.

Madison Stewart feeds Caribbean reef sharks in Shark Girl, a one-hour special. (Ernst Stewart/Courtesy of Smithsonian Channel)

Madison Stewart has been swimming with sharks since she was 12. (Ernst Stewart/Courtesy of Smithsonian Channel)

The film, suggested for age 12 and older, follows Stewart as she dives off the shores of Australia, Mexico, Palau and the Bahamas. Stewart’s mission is to save sharks, especially those that live in the Great Barrier Reef Reserve, where some reports say 80,000 sharks are caught (legally) every year.

The 46-minute film will be shown at 4 p.m. on Sunday, June 8, at the museum’s Baird Auditorium; admission is free. Afterward, Stewart will answer questions from the audience.

For a glimpse of Stewart’s style, check out her short film “Hitchen’s Razor” on YouTube, in which Stewart cavorts with dozens of sharks and in a voice-over issues a challenge: “To me, sharks are family. And nobody threatens my family.”