The largest one of the Princes' Islands. It is a favourite getaway for both locals and tourists, as there is almost no motor transport.
There are plenty of interesting historic mansions to see including the house, where Leon Trotsky lived for four years after his deportation from Soviet Union.
Please check the ferry timetables on the website.
Ticket for regular ferry to the Princes' Islands: 5.20 TL with IstanbulCard, 7 TL with token
Wikipedia https://en.wikipedia.org/wiki/Büyükada
Ferry Timetable http://en.sehirhatlari.istanbul/en/timetable/besiktas-heybeliada-buyukada-3487.html
Coordinates 40°51'29.92" N 29°7'20.66" E