The Office on the Gunlukbasi Road has been closed for a while now, they use the one down by the Marina.
The journey takes 90 minutes. Do not rush to the front of the boat where all the windows are, as it gets very hot in there. Also, on the return journey, get ready to get off and stand near the door before the boat docks, as you have to go through customs, which is a hut with a window and if you are lucky two men working if not only one. A long queue forms and if there are any problems with the person in front and their passport you have to wait a long time. Remember you can also bring back some Duty Free.