Karamürsel in the context of "Gulf of İzmit"

The Ottoman Navy (Turkish: Osmanlı Donanması) or the Imperial Navy (Ottoman Turkish: Donanma-yı Humâyûn), also known as the Ottoman Fleet, was the naval warfare arm of the Ottoman Empire. It was established after the Ottomans first reached the sea in 1323 by capturing Praenetos (later called Karamürsel after the founder of the Ottoman Navy), the site of the first Ottoman naval shipyard and the nucleus of the future navy.

During its long existence, the Ottoman Navy was involved in many conflicts and signed a number of maritime treaties. It played a decisive role in the conquest of Constantinople and the subsequent expansion into the Mediterranean and Black Seas. At its height in the 16th century, the Navy extended to the Indian Ocean, sending an expedition to Indonesia in 1565, and by the early 17th century operated as far as the Atlantic. Commensurate with the decline and modernization of the empire in the late 18th century, the Ottoman Navy stagnated, albeit remaining among the largest in the world: with nearly 200 warships, including 21 battleships, it ranked third after the British and French navies in 1875.