Rihanna and Chris Brown holidaying in Hawaii for her birthday

Pop star Rihanna is enjoying a sunny getaway in Hawaii with her on/off boyfriend Chris Brown as part of her 25th birthday celebrations.

The Umbrella hitmaker marked her special day on Wednesday (20Feb13) and posted an Instagram.com photo of herself in a bikini as she shared the back seat of a car with Brown.

The couple has since been snapped strolling on the beaches of Honolulu, while Rihanna has also been pictured indulging in her love of water sports by enjoying a jet ski ride with her professional surfer pal Makua Rothman.

A source tells Eonline.com, "She looked totally free and like she was really enjoying her birthday."

On Thursday (21Feb13), Rihanna shared an Instagram.com image of one of her birthday gifts - a designer Goyard handbag. She also posted photos of her with Brown and members of her family - and a shot of her birthday cake.