She took a break from tennis to spent time with her boyfriend, Jackie Long, on Miami beach, not far from the home she shares with sister Venus in Palm Beach.
The curvy star showed off her fuller figure in a teeny black string bikini as she swam, photographed her boyfriend and played with seaweed on Miami beach.
Thunder thighs: Serena Williams has become as well known for her formidable figure as her tennis playing
With her thunder thighs and bulging biceps, she is a formidable opponent on the tennis court. She is a former world number one and has won eight Grand Slam singles titles.
But the heavyweight player proved that size isn't everything last week when she lost out at the French Open to diminutive Justine Henin, who went on to claim the women's title.
Serena will have to put aside her loss to face the courts in two weeks time when Wimbledon opens.
She is known to draw strength from her fans' support and her faith as a Jehovah's Witness.
In a prescient posting on her website, and a marked reference to her fluctuating weight, the day before she lost to Henin, Serena wrote:
"I can't thank those of Y'all who were with me through Thick and Thin (literally) enough.
"You know life sometimes come at you strange. One day you are on top of the world, and the next day you are fighting to hold on... physically and mentally.
"U grasp onto a small string that's holding u between sanity and insanity, groping in the dark trying to find the light that can lead u out of the dark tunnel.
"Then and only then u find and realize the true people that are your friends, and the ones that love u dearly:
"The ones that are willing to be there for you whether or not you are extremely successful, or just normal... the ones that don't disappear because u don't have the face of stone.
"So I wanna thank my God Jehovah, my family, and my Fans, my True Fans for being there for me for always supporting me for making me hold on to that string."