Getting to the Islands
Istanbul has two international airports: Ataturk which is on the European Side and Sabiha Gokcen which is on the Asian side, so be sure to check for best flight options to either airport as the journey to the seaports from the airports are equally straightforwards.
From Sabiha Gokcen (Asia): Ferries operate regularly from Bostanci. A taxi from the Airport to the sea port takes roughly half an hour, costing approximately 35/40TL (£15-17). The ferry crossing then takes a further 30 minutes.
From Ataturk/central Istanbul (Europe): Ferries and sea buses depart from Kabatas. A taxi from the airport should take around 30/40 minutes and cost in the region of 45TL (around £20). Choose from either the sea bus (50 minutes/10TL) or the conventional ferry (1hr 10mins/5TL) or the direct boat to Heybeliada (60 minutes 6YTL).
Though slower, the ferries are open-top and offer a unique insight into the Istanbul of old as well as spectacular views of the city from the water, which is such a predominant feature of the city. They are great places to people watch and the salesmen touting all manner of gizmos and gadgets, provided added entertainment.