Sefine Shipyard is a subsidiary of Sefine Denizcilik Tersanecilik Turizm San. A.Ş. and started its activities in 2007. In a short time, it has become one of the leading players in the maritime industry; It has become one of the rare shipyards where new shipbuilding, ship maintenance/repair/conversion services and large steel structure projects can be carried out at the same time.

The shipyard activities are carried out on an area of 250,000 m² in Yalova-Altınova, on the coast of the Sea of Marmara. In addition to the size of the installed area, it stands out as one of the largest shipyards in its region with its high business volume and service diversity. High-level ship maintenance, repair and conversion services are provided with dry docks with a capacity of 90,000 DWT Post-Panamax and floating docks, one with a lifting capacity of 40,000 tons and the other with a lifting capacity of 75,000 tons.

New shipbuilding exports were made to countries such as Norway, Italy, the Netherlands, England, Estonia and the Faroe Islands. World leadership in the construction of Live Fish Transport Vessel has been achieved.

In parallel with the developing technologies, both R&D studies and product delivery processes for new generation autonomous and swarm unmanned marine vehicles are carried out by Sefine Shipyard. Since its establishment, more than 50 shipbuilding projects have been successfully completed; products and services were exported to 43 different countries.

In the "Türkiye's Top 1000 Exporters" research conducted by TİM in 2020, it became the export champion in the Shipbuilding Category.

Since the day it was founded, it has assumed a leading role in the Turkish maritime sector and has employed more than 6000 employees, including subcontractor personnel.

With continuous investments, high export performance, strong R&D and innovation activities, Koloğlu Holding continues to operate.

With the world-class products and services offered, high added value is provided to the sector and the country's economy.