Ivanka Trump's heating up the beach once again ... showing off her surf skills down in Costa Rica -- with supermodel Karlie Kloss by her side!
The First Daughter was spotted in the Central American country Thursday ... hitting the beach and hopping back on her trusty surfboard in the crystal clear ocean water.
Check out the pics ... Ivanka's showing off her bod in an orange two-piece -- soaked in the salty water but looking happy while walking along the beach later on.