The 38-year-old looked almost unrecognisable in photos of herself in a red bikini as she and a friend jokingly practised their synchronised swimming techniques.
"Hey...do you want to pretend we’re synchronised swimmers?" Heidi joked in the caption of the series of snaps.
Her MAFS co-star Nic Jovanovic commented on the snap, "Haha Heidi you are blessed."
Blair Rachael, who also starred on the show, wrote, "OK, this is a major vibe!"
Mishel Karen, who appeared on the reality dating show this year, added, "You look amazing."
"Excuse me while I pick my jaw up from the ground," one follower wrote.
"Bloody hell woman," another user wrote with the heart eyes emoji.
Heidi was paired up with Mike Gunner on the show last year, but despite having a lot of chemistry at their wedding, the relationship soon fell apart.
On the honeymoon Mike said to her, "I'm not your therapist. This isn't therapy," when she tried to have a personal conversation with him.
He later famously told her he could "maybe try and fall in love" with her.
Unsurprisingly, Heidi wished he had simply said nothing at all.
They managed to make it through the entire experiment but split up two days after filming finished.
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