The mountainous structure of Zonguldak province has led to the only transportation option for many years, by sea. Passenger transportation has been carried out in Zonguldak port for many years as well as freight transportation. However, as a result of the development of the road network over time, almost all of the passenger transportation has shifted to the highway.

Zonguldak Port maintains its importance in freight transportation today. After the administration of the Ereğli Coal Mines was given to the Ministry of Maritime Affairs (Naval Ministry), the amount of coal extracted from the Ereğli Basin increased due to the studies and technical developments. However, the coal transfer could not be carried out regularly, coal was damaged and damaged, especially in bad weather, and the transfer was slowed down.

Since there is no harbor for ships in Zonguldak, it was planned to build a breakwater in Kozlu first to ensure faster and easier transfer of coal, but this was abandoned after a short time. The reason is the economic difficulties and conditions of the period. During the Ottoman Empire period, the construction of the port was started in 1898. Caught by storms and winds, the port was destroyed several times while under construction, but it was completed and opened to service within 4 years.