Alessandra Ambrosio Diving in Headfirst, Butt ...

1/12/2017 8:50 AM PST

0112-alessandra-ambrosio-bikini-launch-3Alessandra Ambrosio's soaking up summer in Brazil ... or at least her buns are.

The VS supermodel's purple bikini did its best to hang on in the surf of the resort town Florianópolis.

We'd say this is the best body surfing contest ever, but Alessandra has no competition.