The superstar songstress flaunted her killer body and various tattoos - including the large goddess Isis on her chest - while soaking up the sun in Gdynia before her performance at the Heineken Open'er Festival later that evening.
Sporting a tiny white and pale green two piece and a matching mesh skirt, 25-year-old RiRi appeared effortlessly stylish.
She added some glamour with gold chains, including one spelling out her surname 'Fenty', as well as a brown leather visor and a pair of feline shaped sunglasses.
However, although the 'We Found Love' singer may have looked the picture of perfection for a day of sunbathing, it sounds like she didn't have such a great time.
During the day she took to Twitter to express her disappointment about her beach excursion, tweeting: "Tried to have a beach day, that was a fail!! "
She also uploaded a candid snap to her Instagram, in which she looked rather straight faced while showing off her washboard stomach.
Joining RiRi on her day out was BFF Melissa Forde, who posted a short video of the pop star remarking that she felt as though she was "caged in like a f**king animal" on the beach.
However, the two girls swiftly erupted into giggles, suggesting that they weren't too disheartened.
Meanwhile, back in the States, Rihanna's on-off boyfriend Chris Brown is thought to have reunited with his ex-girlfriend, Karrueche Tran.
Last weekend, Vietnamese model Karrueche posted a photo of herself and Chris together as she wished him "good luck" for his performance at the BET Awards and even referred to him as her "baby".
What do you think of Rihanna's beach outfit? Let us know below!