The Azores, or Açores, is an archipelago of nine Portuguese volcanic islands in the Atlantic Ocean. The island of Terceira is particularly worth visiting because you can visit a Unesco heritage site (Angra do Heroísmo), view a patchwork blanket of green farm fields inside the largest crater of the Azores (Serra do Cume), and walk inside a volcano (Algar do Carvão). Terceira is the third largest island of the archipelago and is thought to be the third island to be discovered.