Tybee Island is a city and a barrier island in Chatham County, Georgia, 18 miles east of Savannah. The name "Tybee Island" is used for both th…Tybee Island is a city and a barrier island in Chatham County, Georgia, 18 miles east of Savannah. The name "Tybee Island" is used for both the island and the city, but geographically they are not identical: only part of the island's territory lies within the city.