Kourtney Kardashian & Travis Barker Take Rocky for a Swim in Portofino

Kourtney Kardashian and Travis Barker's son might be Rocky, but they're not letting him sink in this pool ... keeping him floating as a fam on a picturesque vacation.

The happy couple took their infant to Portofino -- the popular vacation destination in Italy ... hanging out with him and KK's daughter, Penelope, earlier this week.

Mamma Kardashian and Papa Barker are two proud parents in these pics ... holding their son -- clad in his blue shorts and yellow-orange bucket hat -- up above the water and dipping him in.

Travis and Kourtney take turns holding their son ... and, a final image shows Kardashian snuggled up against her man's arm -- planting a kiss on his shoulder.

Rocky's getting a lot more attention in public these days ... 'cause Kourtney and Travis took him on a family outing just last month -- cheering on his dad during a ceremony in his hometown of Fontana.

They also took Rocky on a Blink-182 tour last year ... before he even turned a year old -- so, this kid is already preparing for the limelight.