Fefan is the third largest inhabited island of the Chuuk Lagoon in the Federated States of Micronesia. It has an area of 13.2 km² and a pop…Fefan is the third largest inhabited island of the Chuuk Lagoon in the Federated States of Micronesia. It has an area of 13.2 km² and a population of about 3,000 and is the second largest municipality in the Chuuk State. The northern part of the island is hilly and peaks at 298 meters above sea level.