You can often save a lot of driving time in Turkey by using ferry services. Most operate separate summer and winter services, with services after dark only on major routes.
Within İstanbul and İzmir ferry services not only save time but are the nicest way to get about the city too.
Yenikapı to Yalova (http://www.ido.com.tr/en)
Yenikapı to Bandırma ( http://www.ido.com.tr/en)
Yenikapı to Güzelyalı (for Bursa) ( http://www.ido.com.tr/en)
Kabataş to Güzelyalı (for Bursa) ( http://www.ido.com.tr/en)
Kadıköy to Güzelyalı (for Bursa) ( http://www.ido.com.tr/en)
Eskihisar to Topcular (http://www.istanbullines.com/en/timetables/eskihisar-topcular)
Tekirdağ to Avşa
Avşa to Marmara (http://www.gestasdenizulasim.com.tr/en/index.php)
Çanakkale to Eceabat (http://www.gestasdenizulasim.com.tr/en/index.php)
Çanakkale to Kilitbahir
Çanakkale to Gökçeada (http://www.gestasdenizulasim.com.tr/en/index.php)
Kabatepe to Gökçceada (http://www.gestasdenizulasim.com.tr/en/index.php)
Kepez to Eceabat (http://www.gestasdenizulasim.com.tr/en/index.php)
Geyikli to Bozcaada (http://www.gestasdenizulasim.com.tr/en/index.php)
Gelibolu to Lapseki (http://www.gestasdenizulasim.com.tr/en/index.php)
Eski Foça to Mordögan and Karaburun (peak season only)
Kahta to Siverek
Elazıg to Pertek (for Tunceli)
Keban to Çemişgezek
Malatya to Karakaya (for Elazığ)
Tatvan to Van
Ferry tales: http://www.turkeyfromtheinside.com/blogbloggingaboutturkey/entry/10-rapping-along-the-road-to-diyarbakr-.html
Ferry tales: http://www.turkeyfromtheinside.com/blogbloggingaboutturkey/entry/26-a-forgotten-ferry-route.html
