The Isole Tremiti (Italian pronunciation: [ˈiːzole ˈtrɛːmiti]), also literarily known as Isole Diomedee ("Diomedean Islands", from Greek Διομήδεες Diomḗdees), are an archipelago in the Adriatic Sea, north of the Gargano Peninsula. They constitute a comune of Italy's Province of Foggia, Apulia and form part of the Gargano national park. The archipelago is composed of 5 islands: San Domino, San Nicola, Capraia, Cretaccio, and Pianosa.

The islands were used for the internment of political prisoners during Benito Mussolini's Fascist regime. But it was also the prison of Julia the Younger, the granddaughter of Augustus and, in 780, the prison of Paul the Deacon at the behest of Charlemagne.

The islands are now an important tourist attraction because of the clear waters surrounding them. Up to 100,000 visitors come to the islands in the summer season. Ferry services from the mainland operate from Termoli, Vieste, Rodi Garganico and Capoiale, while Alidaunia offers flights from San Domino Heliport to Foggia and Vieste.