Sally and Nick are pretending to swim, but why not go for a real swim asks the Cat! Off to the Glippydrippy Gulf to meet Matilda the Manatee and her son Marlin. Matilda and Marlon teach their guests how to swim slowly and gracefully. Until they hear the sound of a boat motor! Those can be dangerous for manatees, but luckily the Cat, Nick and Sally help their new friends to stay safe. And when they get back home, Nick and Sally will be sure to tell everyone to "Slow down for manatees!"