The Bosphorus is a hive of bustle and activity, with boats toing and froing between Istanbul's eastern and western shores, from the Sea of Marmara to the Black Sea. A boat trip along the straits makes for a pleasant and relaxing day out, allowing visitors to admire the ornate 19C palaces and yali (wooden houses built in the 18C-19C by state officials) that line the shore. You might also like to visit one of the local fishing villages, the port of Sariyer or stop for lunch in one of the local restaurants, mingling with the locals.