Barbie heads to a tropical island where Ken is doing a marine biology internship. She is accompanied by her pals Chelsea, Skipper and Stacie. The young women go snorkelling to admire the local sealife and they discover a bright green Gemstone Dolphin trapped in an enclosure. It transpires that Ken's biologist team leader, Marlo, intends to make money from showcasing the dolphin to the public. Barbie and her sisters vow to release the creature back into the wild.