About 2-hours. A typical Bosphorus River sightseeing cruise will range from 2 hours to a half-day, 4-hour tour if you want to include things like lunch or stops along the way. You can choose from various cruise offerings of different time durations to spend more or less time on the Bosphorus River while in Istanbul. Getmyboat has over 180 Bosphorus River cruise and water excursion options, so you can customize your tour to your preferences.