Sedef Adası (Sedef Island) is one of the smallest inhabited islands in Istanbul’s Princes’ Islands group in the Sea of Marmara. Covering an area of approximately 1,300 × 1,100 meters, it is the smallest of the islands open to settlement.
The island is known for its quiet atmosphere and natural vegetation, which appears almost shimmering from a distance—one of the reasons behind its name, “Sedef,” meaning mother-of-pearl. In the past, the island was also sometimes associated with rabbits, and local references occasionally included names reflecting this presence, although “Sedef Adası” is the widely accepted name today.
Like many of the Princes’ Islands, Sedef Adası has a history dating back to the Byzantine period, when it was used as a place of exile. One of its most notable historical figures is Patriarch Ignatios, who was exiled to the island in 857. After spending around ten years in exile under difficult conditions across different locations, he was reinstated as Patriarch in 867, marking an important moment in Byzantine religious history.
During the 19th century, the island came into private ownership, including that of Damad Ferid Pasha, a counselor of the Ottoman administration. Under his ownership, olive groves were planted and limited agricultural activity, such as vegetable cultivation, was introduced. However, after his death, the island gradually fell into neglect.
During the early 20th century, particularly around World War I, much of the island’s vegetation was reportedly damaged or cut down. In the following years, the island saw limited strategic use during the final period of the Ottoman Empire and the Allied occupation of Istanbul, including temporary anchoring of naval vessels in nearby waters.
Later, descendants of Damad Ferid Pasha attempted to redevelop Sedef Adası as a residential area for an upper-class community. A housing cooperative was formed, thousands of trees were planted, and several villas were constructed in an effort to transform the island into a quiet, exclusive settlement. While development remained limited, these efforts helped shape the island’s current character as a small but partially inhabited residential area.
Today, Sedef Adası remains one of the most peaceful corners of the Princes’ Islands, known for its natural beauty, low population density, and restricted development. It offers a rare combination of historical depth and tranquil island living within reach of Istanbul.