“North-easterly Wind Village”
Poyrazköy is a small beach resort on the Asian shore of İstanbul beyond Anadolu Kavağı and the Third Bosphorus Bridge. It is the furthest point north you can visit on a public ferry and then only in the summer months.
The beach aside, there’s not a lot to do here. The slight remains of Poyraz Kalesi (castle) overlook a stretch of beautiful rugged coastline and the mouth of the Black Sea but the mosque is florid on the inside, plain on the outside. A row of pleasant breakfast and snack-meal cafes line a ridge looking out over the Third Bridge. A pleasant tea garden is shaded by a venerable plane tree by the beach. And that’s about it. 
Little is known about Poyraz Kalesi. It may have started life as a Genoese fort in the 15th century but was probably rebuilt in the 18th century when Garipçe Kalesi was built on the European shore. Both castles were supplemented with watchtowers constructed in 1778 under the guidance of the French military officer, Francoiş Baron de Tott (1733-93). The circular castle continued in military use until 1988 which means that the brick and stone remains are surrounded by the detritus of what looks like a n abandoned canteen. The site is not officially accessible although there are gaps in the surrounding fence for those prepared to run the risk.
As for the mosque, it was originally commissioned by the admira and grand vizierl, Cezayirli Hasan Paşa (1713-90), in 1782 but extensively remodelled in 1991.
Transport info
Probably the main reason to come here would be to take the ferry under the bridge and into the small Poyrazköy harbour but it can be a rough crossing at both ends of the summer sailing season and sometimes the ferry is cancelled in which case you will have to find your way back to the town centre by bus, probably with a change in Beykoz.
