War on Whimsy — Liane Moriarty

Now that they've saved two planets from destruction, Nicola and her Space Brigaders must take care of Shimlara's family. So they travel to Whimsy -- a beautiful, pink haloed planet where the people lie around in meadows making up poems, playing harps, and creating sculptures. There, they parachute, scuba dive, and white water raft their way to a prison camp, where they rescue Shimlara's family and help the people of Whimsy wage war against the evil, red-scaled beings from Volcomania.