Sedef Adası: The Private Isle of the Princes’ Islands

Sedef Adası – Mother-of-Pearl Island – lies quietly across from Büyükada, the grandest of the Princes’ Islands of Istanbul. The smallest inhabited island in the archipelago measures little more than a speck on the map. It covers an area of 0.1 57 km² and its highest peak is 55 meters.

Its Greek name, Terebintos, hints at the scent of old turpentine trees, once plentiful on these slopes.

Exile found its way here in Byzantine times, while under Ottoman rule, the island was mostly forgotten. It was too small, too bare, offering nothing to cultivate or conquer.

That silence broke in 1850, when Sultan Abdülmecit gifted the island to his son-in-law, Fethi Ahmet Pasha, who commissioned the planting of olive trees and the construction of a summer mansion. But neglect soon followed: By the time of the First World War, even the trees had vanished.

A distant shot of a green, tree-covered island in the sea. The island's hills are dotted with a few houses and buildings, and ships are visible on the horizon. The view is framed by green foliage in the foreground. — A Distant Shot of Sedefadası from Büyükada

The dream returned in the 1950s. Two of the Pasha’s descendants – Şehsuvar Menemencioğlu and Reyan Şehsuvaroğlu – reimagined the island as a haven of modern luxury.

They commissioned architect Kadri Eroğan to lead the transformation. Already known for designing the Tarabya Hotel, one of Istanbul’s earliest modern landmarks, he oversaw the construction of sleek villas and the restoration of the island’s greenery. This project shaped Sedef Island’s rebirth in the spirit of mid-century modernism.

Today, the island attracts attention for its exclusivity, luxurious villas, and beautiful beaches. Since most of the island is private property, visitors cannot walk around the entire area. There are no seaside cafés, shaded promenades, hills with sweeping views, or cultural landmarks.

A wide-angle view of a heavily wooded island in the Sea of Marmara, with scattered houses visible on its hillsides and several boats anchored near the shore. — A Distant shot of Sedefadası from Istanbul Side

For visitors without friends or family here, Sedef Adası reveals itself through two public spaces: a restaurant with access to a pebble beach and an exclusive summer club, which Istanbul’s high society favors as a discreet place to be seen. There is also a single grocery store, practical and modest, tucked quietly away.

For the curious: unless you arrive with an invitation, your passage here comes by private boat. A select few take the co-op ferry from Kartal, a quiet vessel ferrying the island’s residents and their guests across the shimmering sea.

A view of a beach club on Sedef Island, with rows of white and black sun loungers and umbrellas on a concrete platform. A blue water slide is visible on the left, with two small boats and a wooden pier in the calm sea. — A view of Sedef Island Beach Club

So, Sedef Island doesn’t attract tourists. It’s less a destination and more a whispered secret. If you can’t swim well or don’t own a boat, you might want to reconsider your weekend plans.