Bikini-clad Katharine McPhee flaunts abs while celebrating 40th birthday on boat

Katharine McPhee is in her birthday (bathing) suit!

The “American Idol” alum celebrated her 40th year on a boat with her husband, David Foster, and their friends.

“It’s been such a magical week!” the singer captioned sunny snaps via Instagram Wednesday. “Thank you all for all the birthday love.”

The actress covered up in a mesh dress. katharinefoster/Instagram
She showed off her “magical” party via Instagram. katharinefoster/Instagram
“Turning 29 isn’t so bad,” the singer joked. katharinefoster/Instagram
She posted sunny snaps ringing in her new year with friends. katharinefoster/Instagram

McPhee jokingly concluded, “I guess turning 29 isn’t so bad 🤣🫶🏻.”

The actress put her abs on display in the social media upload as she partied in a blue bikini and a straw hat.

She covered up later on in a yellow and white mesh dress, completing her laidback look with strappy sandals.

The boat was decorated with balloons. katharinefoster/Instagram
Her friends enjoyed a breakfast spread. katharinefoster/Instagram
McPhee’s husband, David Foster, drank a piña colada. katharinefoster/Instagram

The “Country Comfort” star gave her followers a glimpse of her party decor on board the boat, from silver “HAPPY BIRTHDAY” balloons to a delicious spread of fruit, waffles and more breakfast items.

She also showed a “new” version of her 74-year-old husband enjoying a “piña colada, baby, with booze.”

The couple, who have been married since June 2019, often clap back at criticism about their 34-year age gap.

The couple got married in 2019. Instagram/@katharinefoster
They share 3-year-old son Rennie. Instagram/@katharinefoster

McPhee “totally gets the judgment,” telling “Dr. Berlin’s Informed Pregnancy Podcast” listeners in a 2021 episode that she was initially “very concerned with what people [would] think” of their romance.

“We had a real journey, and I had a real process,” she explained. “It took me a while to kind of come around to really want to have a real, serious relationship.”

The “Smash” alum was married once before to Nick Cokas, while Foster’s ex-wives include B.J. Cook, Rebecca Dyer, Linda Thompson and Yolanda Hadid.