A cheap way to explore the Bosphorus is offered by the public ferries that traverse the Bosphorus from Eminönü (ferries dock at the Boğaz İskelesi) on the historic peninsula of Istanbul to Anadolu Kavağı near the Black Sea, zigzagging between the Rumelian and Anatolian sides of the city.
It is also possible to experience the Bosphorus by taking a regular ride in one of the public ferries that travel between the European and the Asian sides. It is also possible to travel by the privately owned ferries available between Üsküdar and Beşiktaş or Kabataş.
There are also tourist rides available in various places along the coasts of the Bosphorus. The prices vary according to the type of the ride, and some feature loud popular music for the duration of the trip.(wikipedia)