The Eminonu Pier is located along the southern end of the Galata Bridge and consists of multiple docks for ferries cruising along or crossing the Bosphorus.
Eminonu Halec Iskelesi (dock) is the furthest west of the docks and is the departure point for Sehir Hatlari Golden Horn ferries. The other dock west of the Galata Bridge, the TurYol Eminonu dock, is where you will find TurYol ferries to Uskudar, Haydarpasa and Kadikoy, as well as Bosphorus cruises. Follow the pedestrian way under the Galata Bridge and you will come to remaining five docks, with ferries heading to Uskudar and Kadikoy, as well as a car ferry heading to the Harem Otogar on the Asian side of Istanbul and multiple ferries cruising across the Bosphorus.
Before or after your ferry journey, try a fish sandwich from a boat at the pier, peruse the goods being hawked by merchants along the pier and sample some of the bites offered by other vendors.
Eminonu Pier is within easy walking distance from much of the old city and lies just over the Galata Bridge from Beyoglu. From further afield in Istanbul, you can catch the tram to the Eminonu station or, of course, jump on a ferry.