Heidi Klum is proof ice cream does the body good.

The supermodel showed off her physique Sunday in a black string bikini while on vacay in St. Barts. The 44-year-old smoke show was there with her boyfriend, Vito Schnabel, and her family.

Vito had his usual front row seat for the Heidi show ... as she caught waves and got down and dirty in the sand. If you look closely, there was also a unicorn sighting on the beach.

Anyone else got a sweet tooth?