Heidi Klum, 51, goes TOPLESS on the  beach as she packs on the PDA with husband Tom Kaulitz, 34, during their anniversary celebration in St. Barts

Heidi Klum showed off her supermodel physique by going topless on the beach with her husband Tom Kaulitz in St. Barts on Sunday. 

The 51-year-old supermodel — who has been called a 'cougar' for the 17-year age gap between her and Kaulitz, 34 — left little to the imagination as she soaked up the sun in nothing but a thong bikini bottom. 

The German bombshell radiated raw sex appeal as she playfully danced in the surf and sand. 

Tom was captured embracing the TV host during their spirited swim, sharing a tender kiss as they enjoyed the moment. 

The seaside outing follows Heidi's recent Instagram tribute celebrating her and Tom's five-year anniversary. 

Heidi Klum showed off her supermodel physique by going topless on the beach with her husband Tom Kaulitz in St. Barts on Sunday

The 51-year-old supermodel — who has been called a ' cougar' for the 17-year age gap between her and Kaulitz, 34 — left little to the imagination as she soaked up the sun in nothing but a thong bikini bottom

The romance between the Project Runway alum and Tokio Hotel guitarist first caught public attention in March 2018, when they were seen sharing a passionate kiss while leaving a Lorraine Schwartz launch party, linked arm-in-arm.

Their relationship quickly intensified, and by December 2018, Kaulitz proposed. 

The couple exchanged vows in a private ceremony just seven months later, before celebrating with a grand event in Capri, Italy, in August 2019.

Following their wedding, Tom embraced his role as a stepfather, joining Klum in raising her children. 

Klum has a daughter, Leni, with former boyfriend Flavio Briatore, and sons Henry, Johan, and Lou with her ex-husband Seal, to whom she was married from 2005 to 2014.

The exes also share sons Henry, 18, Johan, 17, and Lou, 14. 

During their marriage, he also adopted her daughter, Leni, now 20, when she was just five-years-old. 

Meanwhile, Heidi's topless adventure comes after she revealed she's unapologetic about sharing topless or nearly naked photos. 

Tom was captured embracing the TV host during their spirited swim, sharing a tender kiss as they enjoyed the moment

The German bombshell radiated raw sex appeal as she playfully danced in the surf and sand

The seaside outing follows Heidi's recent Instagram tribute celebrating her and Tom's five-year anniversary

The romance between the Project Runway alum and Tokio Hotel guitarist first caught public attention in March 2018, when they were seen sharing a passionate kiss while leaving a Lorraine Schwartz launch party, linked arm-in-arm

The pair were inseparable on the beach

She also said that there’s a 'strategy' behind her love for showcasing her figure.

'I’m super comfortable naked today. To the point where my kids are like, "Mom, I have a friend coming over,"'' she told People in 2023.

'As soon as someone is coming, I put my top on,' Heidi explained. 'But if no one is there, suns out buns out. 

'I just don’t like tan lines because I wear so many different outfits. I don’t want to have straps anywhere from tan lines. It’s very strategic.'

She continued: 'When I do America's Got Talent, most of the time I sit behind a desk, so it's really from the waist up.'

'So, I look for something that is of interest around here. 

The couple exchanged vows in a private ceremony just seven months later, before celebrating with a grand event in Capri, Italy, in August 2019

Their relationship quickly intensified, and by December 2018, Kaulitz proposed

Following their wedding, Tom embraced his role as a stepfather, joining Klum in raising her children

Klum has a daughter, Leni, with former boyfriend Flavio Briatore, and sons Henry, Johan, and Lou with her ex-husband Seal, to whom she was married from 2005 to 2014

The exes also share sons Henry, 18, Johan, 17, and Lou, 14

Heidi's topless adventure comes after she revealed she's unapologetic about sharing topless or nearly naked photos

'And usually, I like to have Hans and Franz on a good display,' she quipped while motioning at her breasts. 

She also insists she takes fitness and diet seriously to maintain her fit figure.

In a 2021 interview with Body and Soul she said, 'I try to eat super healthy. We eat at like 6 to 6:30pm, [and having] home-cooked food, knowing what you're eating is super important. 

'I love healthy food; I don't really eat much junk. I like to be fit and I like to feel fit. I know that when I gained a little bit [of weight]... I felt sluggish. I was like, "No, I have to get back into shape."'