500 Ekueles Annobón island

Annobón is a volcanic island of roughly 17 square kilometers lying some 350 kilometers southwest of São Tomé, historically so isolated that its Portuguese Creole dialect — Fa d'Ambô — survived largely intact centuries after Portuguese administration ended. Equatorial Guinea acquired the island from Spain in 1968 but has long treated it as an afterthought; residents have periodically protested neglect and sought autonomy. A commemorative issue naming the island specifically is an unusual acknowledgment of a territory the central government in Malabo rarely highlights.