Ashlee Simpson: Bikini Babe in Hawaii!

Ashlee Simpson shows off her flawless bikini body while taking a dip in the water with her son Bronx on Saturday afternoon (December 29) in Oahu, Hawaii.

The 28-year-old entertainer wore a mismatched swimsuit and a New York Yankees hat on the sunny day out.

PHOTOS: Check out the latest pics of Ashlee Simpson

Back in California, Bronx‘s dad Pete Wentz went shopping at American Rag in West Hollywood with his girlfriend Meagan Camper.

Earlier in the week, Ashlee and Bronx built sand castles on the beach.

25+ pictures inside of Ashlee Simpson showing off her bikini body…