Ireland Baldwin goes paddle boarding with boyfriend Slater Trout in Hawaii on May 26, 2013. Credit: Splash News

Alec Baldwin's only daughter is all grown up! Ireland Baldwin spent Memorial Day weekend in Hawaii with her beau, professional waterman Slater Trout, looking like a pro on her paddle board as the couple navigated through the clear waters of Maui, Hawaii on Sunday, May 26.

Baldwin, 17, wore a tiny string bikini for the afternoon outing, showing off her enviable beach body as she paddled through the waves with beau Trout, 18, not too far behind.

Earlier in the day, Trout took to his Instagram account to share some adorable photos of the two of them, captioning one shot: [Ireland] shaved my beard this morning while I was sleeping & then I took this intense self. I feel like a little boy."

The pair have been spotted out and about before, engaging in major PDA at the Coachella Music Festival this past April. "Coachella happy with Slater Trout," she captioned one shot of herself sitting on Trout's lap.

Aside from Trout, Baldwin's biggest focus of the moment has been on her modeling career. In a lengthy open letter on her Tumblr in April, she addressed the "haters" who had been making fun of her figure and her family online.

"What I don't fully understand is, what is the good in commenting on a photo of a 17-year-old girl and calling her fat, ugly, etc.? Is that helping you in some way?" she wrote. "I'm confused … putting that out there is hateful and unhealthy. If you don't have a complimentary thing to say about someone, keep it to yourself … It's bad energy being put out there!"