The reality star has had dark brown hair for as long as we can remember - literally, she's hardly even had any highlights. So, this pic was a big shock for us.
"Shipwrecked," Kourt captioned the throwback pic of herself, looking a lot sexier than we would picture someone looking after a shipwreck - you know, because you're more worried about staying alive than making sure your swim style is on point.
Kourtney is certainly not the only Kardashian/Jenner sister to experiment with blonde hair. Kendall Jenner recently rocked the blonde (also for a photoshoot), which kind of blew our minds because she looked like a totally different person. That's Kenny on the right...
And sister Kim Kardashian dove right into the deep end and actually went platinum, for real.
Khloe Kardashian is rocking pretty light hair these days, too, but second to Kylie Jenner, Khlo probably switches up her style the most.
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Gallery | Celeb Hair: Blonde vs. Brunette