Twilight's Kristen Stewart twinkles in a white bikini on romantic sea frolic with Robert Pattinson

She's know for being dark and brooding, but  looked white hot in a tiny bikini while taking a beach break with Robert Pattinson.
Newly-released pictures of the couple show them playfully stripped down and swimming together in the ocean in Brazil.
Kristen, 20, looked toned in her bandeau two-piece as she emerged from the water with her wet hair slicked back.

Bikini break:  looks toned as she takes swim with Rob Pattinson while filming the latest Twilight movie

Robert, 24, seemed in very high spirits as the pair cavorted together.
He took a running jump into the water wearing only his underwear.
Clad in a pair of black Calvin Klein boxers, the Twilight star was taking time out from filming Breaking Dawn, the latest instalment in the vampire saga.
As Robert leapt yelling over Kristen's head, she ducked low in the water and grimaced at the oncoming splash from her boyfriend.

Lovers leap: Robert Pattinson takes a running jump over girlfriend  's head as they relax in the pool during a pause in filming

Witnesses also spotted Kristen jumping on Robert's back for a piggyback ride.
The pair were also seen filming steamy kissing scenes on the streets of Rio De Janeiro last month.
Twilight: Breaking Dawn is set for release on Nov 18th, 2011.
In the meantime Kristen fans can see her current film, Welcome To The Riley's, in which she plays an under-age stripper.

Passionate: Kristen and Rob filmed honeymoon scenes that included a kiss on the streets of Rio