Nina Agdal Credit: TK

How in the world do you follow up a (topless) Sports Illustrated swimsuit issue cover with? More swimwear modeling, of course!

Fresh from her soaking-wet SI cover with Chrissy Teigen and Lily Aldridge, Nina Agdal shows off her bikini body yet again in the new ad campaign for Op -- and Us Weekly has the first look at the sizzling shoot! Posing on the beach with Dallas actor Josh Henderson and Cailin Russo of Justin Bieber music video fame, the Danish native looks smoking hot in the brand's surfwear-inspired string bikinis and monokinis. Henderson keeps up with the ladies with and without his shirt (you can guess which we like best!) while Russo shows off her lean body in bikinis and short shorts.

"My favorite piece of the day was definitely my one-piece crochet swimsuit. It was really fun and colorful," Agdal, 21, said in a press release. "Op was one of the first companies to take the surfing style and make it more fashionable. I love that they still keep it cool and California-like, but chic."

Agdal, Hendersen, and Russo join an esteemed list of Op spokespeople including Kellan Lutz, Ashley Tisdale, Sarah Hyland, and Chord Overstreet.

The sexy styles seen in the "Sunshine State of Mind" campaign will be sold for less than $40 (most of the swimwear will be under $20!) exclusively at Walmart and beginning in April.