Sienna Miller: Bikini Babe in Ibiza

Someone --give that girl a cheeseburger!

Actress Sienna Miller shows off her extremely thin frame as she romps on the beach in a white bikini while on vacation in Spain.

Sienna Miller: See more bikini photos

The British beauty -- who’s been hard at work promoting her new action flick, GI Joe: Rise Of the Cobra -- is enjoying some downtime, vacationing in Ibiza, on Thursday.

Sienna, who’s been linked to a series of men including (married) actors Balthazar Getty and Jude Law, soaked up some sun and downed a few drinks with her rumored new boyfriend, DJ George Barker.