Emirgan Park is a lovely place to spend some time in greenery away from the city.  It overlooks the Bosphorus in the suburb of Emirgan. The park, one of the largest in Istanbul,  has lovely gardens, a grotto, fountains, quiet picnic areas, and three restaurants housed in former Ottoman Palaces.  One, open only during the summer, is a branch of a well-regarded restaurant in the central city.  The park includes playgrounds and a checker/chess area for children  where pint-sized seating and chess boards surround a super-sized, walk-on board with giant chess pieces.  The Sakip Sabanci Museum is located just outside the park  In the spring the park hosts a  tulip festival.  You can get to Emirgan Park by ferry from Bebek  or one of the buses that follow  the route up the European side of the Bosphorus.  From Kabatas you can take buses: 22, 22RE, and 25E.  From Taksim or Besiktas: 40, 40T or 42T.  If you tell the bus driver where you are going when you get on the bus he will let you know when you have gotten there.