English: This astronaut photograph highlights the metropolitan area of Izmit along the northern and eastern shores of the Sea of Marmara, at the end of the Gulf of Izmit. Commercial and industrial centres—including petroleum refineries and automobile factories—are recognizable by large structures with white rooftops. The smaller city of Gölcük on the southern shoreline of the Gulf is the location of a Turkish naval facility and another automobile factory. Both urban areas are built primarily on flat lowlands adjacent to the Gulf, with green vegetation marking highland areas to the north of Izmit and south of Gölcük.