Five years old. That’s how old Kym Karath was when she walked onto the set of one of the most successful movies in history. She played Gretl, the youngest, "the pink one" as some fans call her, and arguably the most adorable member of the von Trapp brood.
Honestly, it’s hard to imagine the film without her. She’s the one who needs to be carried up the stairs. She’s the one who forgets her lines in the puppet show (on purpose, in the script). But there is a massive amount of trivia and even some pretty heavy real-life history behind the character of Gretl in the Sound of Music that most casual viewers totally miss.
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The Near-Drowning and the Boat Scene
You know the scene. Maria and the seven children are in a rowboat, they stand up to wave at the Captain, and—splash—they all end up in the lake. It’s a hilarious, lighthearted moment.
Except it wasn't for Kym.
Basically, Kym Karath couldn't swim. She was five. During the filming of that iconic lake dunk, the plan was for Julie Andrews to fall forward and grab Kym immediately. It didn't happen like that. Julie fell backward, the boat tipped the wrong way, and Kym went under.
Heather Menzies (who played Louisa) ended up being the one who actually pulled her out. Kym had swallowed so much lake water that she actually threw up on Heather afterward. Not exactly the "Sound of Music" magic you see on screen, right? To this day, Karath has mentioned in interviews that she still isn't a huge fan of water because of that afternoon in Salzburg.
Gretl in the Sound of Music: Fact vs. Fiction
If you’re a history buff, you’ve probably realized by now that Hollywood took some... liberties. Huge ones.
The real von Trapp family did not have a daughter named Gretl. In real life, the youngest of the original seven children was a girl named Martina. She was born in 1921. By the time the family actually fled Austria in 1938, Martina wasn't five—she was seventeen.
Why the name change?
- The musical’s creators, Rodgers and Hammerstein, wanted a more rhythmic, "stage-friendly" set of names.
- Martina became Gretl.
- Rupert became Liesl (yes, the oldest was a boy in real life).
- Werner became Kurt.
The real Martina was reportedly a bit shy, much like the character of Gretl in the Sound of Music, but she didn't spend the escape being carried on her father’s back. For one thing, they didn't hike over the Alps. They took a train to Italy.
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Why a Stunt Double Carried Her in the Finale
Watch the very last shot of the movie. The family is climbing the mountain toward freedom. The Captain (Christopher Plummer) has Gretl on his shoulders.
Wait. Look closer.
That isn't Kym Karath.
By the time they got around to filming the final mountain crossing, several months had passed since they started. Kym had grown. More importantly, she’d been enjoying the Austrian cuisine. Christopher Plummer, who was famously a bit grumpy during filming (he nicknamed the movie "The Sound of Mucus"), complained that she had become too heavy to carry up the incline.
He requested a lighter stunt double. So, the "Gretl" you see in those wide, sweeping shots of the Alps is actually a local Austrian child who weighed a lot less than the real actress.
Life After the von Trapps
Kym Karath didn't just disappear into the Salzburg mist after 1935. She stayed in the industry for a while. You've probably seen her in The Brady Bunch, Lassie, or Lost in Space.
But her story takes a turn that’s a lot more serious than any musical number. As she reached her teens, she began to see the darker side of Hollywood. In a 2025 interview with The Times, Karath opened up about why she eventually walked away. She cited "scary offers" and predatory behavior from powerful men in the industry. It’s a sobering reminder that while we see a sweet five-year-old on screen, the person behind the character was navigating a very difficult industry.
She eventually moved to Paris, studied art history, and modeled. Today, she is a fierce advocate for adults with special needs. Her son, Eric, was born with disabilities following a bout of viral meningitis as an infant. Karath co-founded the Aurelia Foundation to help people like her son transition into adulthood with proper support.
What You Should Do Next
If you’re a fan of the movie, don’t just stop at the screen. To get the full picture of the "real" Gretl and her siblings:
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- Read Maria von Trapp’s original memoir, The Story of the Trapp Family Singers. It is wild how different it is from the movie—they were much more into sacred choral music than "The Lonely Goatherd."
- Watch the 2015 "hidden" reunion clips. The cast remained incredibly close (they called themselves the "Non-Trapps") and their behind-the-scenes stories provide a lot of context for the chemistry you see in the film.
- Check out the Aurelia Foundation. If you want to support Kym Karath's current passion, looking into her advocacy work for the special needs community is the best way to see the woman she became after the pigtails and party dresses.
The character of Gretl in the Sound of Music represents innocence and the heart of the family. Knowing that Kym Karath took that "youngest child" energy and turned it into a life of real-world advocacy makes the movie feel even more meaningful.