Heidi Klum -- Topless Vacay with Younger Boyfriend

Heidi Klum's new boyfriend, 27-year-old Vito Schnabel, went topless yesterday as he palled around in the ocean with Heidi in Tulum, Mexico.

Oh, did we mention SHE WAS TOPLESS TOO?!?!?!?

Schnabel is an art dealer in New York City. He's been previously linked to Demi Moore, Elle Macpherson and Liv Tyler. His father is Julian Schnabel ... director of films like "The Diving Bell and the Butterfly," "Before Night Falls," and "Basquiat."