Both cruise ship ports used for Istanbul are centrally located, and not far from the city center. It's recommended that passengers either take the local tram or taxi service to the city center, which is a few miles away. Once you reach the city center, you'll be able to walk between attractions and landmarks easily until it's time to return to the ship. Most Istanbul sights are not more than 30 minutes away from the cruise port, so everything you'll wish to see and do is located within minutes' drive.
For more info, see our feature Istanbul Port FAQ