The Prince Islands (Turkish: Prens Adaları, from the historic Greek name Prinkēpōn nēsoi (Πριγκήπων νήσοι), alternatively written as Princes' Islands in which the "princes" are plural (meaning "Islands of the Princes"); or Kızıl Adalar ("Red Islands") in Turkish); officially just Adalar ("Islands"), are an archipelago off the coast of Istanbul, Turkey, in the Sea of Marmara. The islands constitute the Adalar district of Istanbul Province.