When Courtney Robertson signed up for the winter 2012 edition of “The Bachelor,” she vowed to treat her relationship with Ben Flajnik like any other. So when they were filming in Puerto Rico and she had an urge to skinny-dip with her suitor in the Atlantic, she didn’t hold back.

The viewers saw Robertson with her arms wrapped around Flajnik’s neck, the waves breaking against them. But what was going on underwater wasn’t nearly so PG.

“To answer your question, yes. Ben and I did have sex in the ocean. On-camera,” Robertson reveals in her new memoir.

PHOTOS: Bachelor stars' scandalous pasts

The raven-haired beauty was dubbed a “man-eater,” “liar” and “mean girl” by other contestants during her stint on Season 16 of “The Bachelor.” Her caustic jabs at competitors during the confessional interviews, and take-no-prisoners focus on Flajnik, made her a lightning rod for tabloids. But Robertson, 30, estimates that less than one percent of the footage shot ended up airing — and she’s dishing on the other 99 percent in “I Didn’t Come Here to Make Friends: Confessions of a Reality Show Villain,” out June 24.

When Robertson made it to the infamous Fantasy Suite round, she was surprised to find her producer pals left plenty of rose petals and candles — but no condoms.

Not that it stopped her and Flajnik from having sex. Three times. (It was the first time they were completely alone, without cameras.)

Robertson was given the final rose plus a whopping $80,000 Neil Lane sparkler as she accepted Flajnik’s proposal in the finale. Nonetheless, the pair split for good a few months after the show’s finale.

Click here to read more quotes from her tell-all from the New York Post.