Walking along the Bosphorus: Starting from Bebek towards Rumeli Hisari, you can do the most scenic walking route of Istanbul. There are many benches with picturesque views and even outdoor gym equipments.
You have 12 hours in Istanbul. Where would you go? Its a hard decision to make. There are plenty of choices and alternatives.
Would you go see the old city and visit the most famous temples of Istanbul: Hagia Sophia, Blue Mosque or Suleymaniye Mosque or do you fancy having a private cruise along the Bosphorus Strait and afterwards sit down for a relaxed lunch at one of those nice fish restaurants?