Fitness Model Katelyn Runck Sizzles In A Ruffled Blue Bikini With A Thong Back: 'She Is A Mermaid On Dry Land'

Fitness model Katelyn Runck revealed that she wanted to "make some waves" in her latest Instagram update, and her 1.9 million followers responded to her set of bikini photos and video with a flood of enthusiastic comments.

On Sunday, the 28-year-old fitness instructor took to Instagram to promote Salty Mermaid brand swimwear. Her post fittingly included a comment about how Katelyn feels like a mermaid trapped on dry land. The social media share also included a set of three photos of Katelyn wearing a Salty Mermaid two-piece, as well as a video of the bathing suit in motion.

The brunette beauty's ocean blue bikini was fin-free, but it did feature a frill. Her tiny, low-rise bottoms were trimmed with a large ruffle on the waistband, which was positioned dangerously low on her sculpted hips.

Katelyn's top featured a twist detail in the middle and a thin strap under the bust. The band was the same size as her top's spaghetti straps. The garment plunged down in a wide V that exposed a generous amount of Katelyn's voluptuous cleavage. The bikini didn't cover up much of the model's athletic frame, including her washboard abs and muscular thighs.

Katelyn also shared a snapshot of the rear of her bathing suit. This second photo revealed that her bottoms had a thong back that exposed her pert derriere. A small ruffle adorned the tiny triangle of fabric that covered up a small segment of her lower back. Katelyn's top had a lace-up back and crisscross shoulder straps.

In her second and third photos, Katelyn showed off the full length of her long legs, including her toned calf muscles. Her post also included a video of the model trying out a few different poses.

For her beauty look, Katelyn sported lengthy curled lashes, dark eyeshadow, and a glossy petal pink lip. She wore her long brunette tresses down.

According to her geotag, Katelyn's photos were taken in Malibu, California. She was pictured posing in front of a wooden door in most of her snaps and in her video.

While the point of her post was to sell swimsuits, many of the comments it inspired were about Katelyn's fit figure, not the bikini she was wearing.

"I salute you for the great shape you are in to get your body looking like this," wrote one fan.

"Loved the physique..... one of the most amazing and stunning model on the world," another admirer gushed.

"Super super stunning lady with one hell of a body," read a third response to her post.

Even when she isn't trying to sell bikinis, Katelyn often rocks swimsuits in her promotional snapshots. As previously reported by The Inquisitr, the model recently wowed her fans by sporting a yellow string bikini in an ad for a sports drink.