Cruising down the Bosphorus is one of the most popular tourist activities in Istanbul, but most people will pay way too much (50 Turkish lira/$40 or more) to sit on a crowded, privately owned boat for three hours without every really getting the chance to interact with local culture. The public Bosphorus ferries are a bit better, at 25 lira ($20) round-trip, and they're of locals traveling to the outer areas of the city, but there is an even better option: the Golden Horn. This curved estuary that divides the historic Pera and Sultanahmet neighborhoods stretches over 7 kilometers inland from the Bosphorus, and was in historic times Istanbul's primary harbor.

Golden Horn Ferries
Primarily a transit line for the many residential neighborhoods that line the Golden Horn, these ferries offer insight into local life and culture that the more touristy Sulanahmet area by the Blue Mosque and Hagia Sophia will rarely give. Any stop along the line offers the chance to walk through streets teeming with small shops and local restaurants, but many of them also have one or two attractions that can serve as a focal point for your visit. Choose a couple of neighborhoods from this list, or just hop off the ferry at whichever grabs your interest:

Karaköy
On the Galata side at the mouth of the Golden Horn, the Karakoy neighborhood is a great place to eat before or after a ferry trip. Just on the north side of the Galata bridge is a market with excellent fresh seafood, while the neighborhood to the south is home to the famous Karakoy Gulluoglu baklava shop  -- the oldest in Istanbul.

Kasımpaşa
Turkish Baths are truly incredible, and while those in the Cemberlitas and Sultanahmet neighborhoods are targeted at (and priced for) tourists, the Buyuk Hamam in Kasimpasa is a very local experience. As per local norms, bathing areas are separated into male and female sections.

Hasköy
On the approach to the Haskoy ferry stop, you may notice a submarine docked a bit further up the Golden Horn. The Rahmi Koc Museum here offers exhibits on the history of industry, transportation, and communications in Turkey. With a number of historic ships and cars on display and occasional temporary exhibitions, this is a good stop for the informationally inclined. Those looking for a pretty view would get more out of a visit to the Aynalikavak Palace. With decorations reminiscent of the 1700’s-era Ottoman Empire, this rarely-visited Imperial pleasure pavilion is a quiet respite from the crowds at the more popular palaces like Topkapi and Dolmabahce.

Ayvansaray
Though the Tekfur Palace here (the only remaining Byzantine Palace in Istanbul) has been closed since 2006 for renovations, even the exterior is worth the walk. The surrounding neighborhood, Balat, was traditionally a Jewish quarter and some of the remaining historic buildings here bear Stars of David and other identifying marks. For aimless strolling, this is one of the better choices along the Golden Horn.

Eyüp
The only part of the Golden Horn that sees many tourists, Eyup is home to a famous café and even more famous mosque. The Eyup Sultan Mosque is an important pilgrimage site for Muslims, said to be the burial location of the standard-bearer for the prophet Muhammed. From the mosque, a path leads uphill through a historic cemetery to the Pierre Loti Café, the single best overlook from which to see the whole Golden Horn and a really spectacular place to catch a sunset in Istanbul.

Practical Information
Ferries leave from Uskudar and Eyup on the half hour from 7:30 a.m. (10:30 a.m. on Sundays) until 7:30 p.m.. From Karakoy, the most convenient departure point for the majority of travelers, the ferry stop is just south of the end of the Galata Bridge. Look for the sign that reads “Halic.” Ferries cost 3 Turkish lira ($1.40) per ride, so the total cost will depend on how many stops you make along the route. A timetable for the Golden Horn Ferries can be found here.