Rihanna magnificents “Green Bikini” Butt & Ass in Sardinia

Rihanna, 24, posed in her bikini as she flaunted her body while posing a number of positions on the luxury boat.

She was joined by two girl pals, who also tweeted photographs of the singer in her summery finest.

Letting her hair down: Rihanna's friend shared some more intimate pictures of the singer during the sunny outing (Read more and See more Pictures)