Zonguldak (Turkish pronunciation: [zoŋˈguɫdak]) is a city of about 100,000 people in the Black Sea region of Turkey. It is the seat of Zonguldak Province and Zonguldak District. It was established in 1849 as a port town for the nearby coal mines in Ereğli. The current mayor is Tahsin Erdem, representing the CHP.

There are several different theories concerning the origin of the city's name:

In a 1920 report, the British Foreign Office spelled Zonguldak Zunguldak.

The city is a major centre of chestnut honey production, with most of Turkey's output originating from the region. The city is nicknamed kestane balının diyarı (lit. 'chestnut honey realm') as a result.

The port city of Zonguldak suffered a heavy bombardment by the Russians during World War I, according to the caption of a Lubok popular print.

In 1920 the port was under the control of the Heraclea Coal Company. The northern part of the bay featured a man-made harbor, for steamship use. At that time, they had two cranes which distributed coal to exporting vessels. There is a mining museum.

According to the Köppen climate classification, Zonguldak has a humid subtropical climate (Cfa), though it was, until recently, considered to have an oceanic climate (Cfb), with its warmest month being well below the 22 °C threshold. In recent decades climate change and the city's urban heat island has warmed the city enough to change its classification. Summers are warm, the average temperature is around 22.5 °C in July and August. Winters are cool, the average temperature is around 6 °C in January and February. Precipitation is frequent, while it is generally heaviest in autumn and early winter, lightest (although still frequent) in spring. Snow is sporadic in winter, but is heavy once it occurs.

The water temperature is cool to mild and fluctuates between 8 °C and 20 °C throughout the year.