Hereke

Charax in Bithynia (Ancient Greek: Χάραξ της Βιθυνίας or Χάρακας της Βιθυνίας) was a Roman and Byzantine port town of ancient Bithynia, in what is now Turkey. It was on the north side of the Sinus Astacenus on the road between the erstwhile Eastern Roman and Byzantine capital Nicomedia and Libyssa. Stephanus of Byzantium calls it a place of great trade.Its site is located near Hereke, in Asiatic Turkey.

The Hereke Tunnel (Turkish: Hereke Tüneli), is a motorway tunnel constructed on the Istanbul–Ankara motorway O-4 E80 in Kocaeli Province, northwestern Turkey. It was opened to traffic in 1984. It is situated in Körfez district of Kocaeli Province. The 281–285-metre (922–935 ft) long twin-tube tunnel carries three lanes of traffic in each direction. The tunnel was constructed in the 1980s. During the 1999 İzmit earthquake, the tunnel was light damaged. In 2012, the tunnel's both tubes were reinforced. In the time period of 2013–2014, the tunnel was modernized for traffic safety. Around 55,000 vehicles pass through the tunnel in both directions daily.

Gulf of İzmit (Turkish: İzmit Körfezi), also referred to as Izmit Bay, is a bay at the easternmost edge of the Sea of Marmara, in Kocaeli Province, Turkey. The gulf takes its name from the city of İzmit. Other cities and towns around the bay are Gebze, Körfez, Gölcük, and Altınova. In the east–west direction, it extends for a length of about 48 kilometres (30 mi), while in the north–south direction its width varies from 2 to 3 kilometres (1.2 to 1.9 mi) at the narrowest spots to about 10 kilometres (6.2 mi) at its widest. The İzmit Bay Bridge is a suspension bridge that bridges the gulf. The North Anatolian Fault Zone, the most prominent active fault in Turkey and the source of numerous large earthquakes throughout history, passes through the Gulf of İzmit.

Tavşancıl railway station was a railway station in Tavşancıl, Turkey on the Istanbul-Ankara railway. It was located in the southern part of the town on the shore of the Gulf of İzmit. The station was a stop on the Adapazarı Express regional train service; 11 daily eastbound trains and 13 daily westbound trains stopped at Tavşancıl. The opening date of the station is unclear, but the station was rebuilt and expanded in 1975, when the Turkish State Railways double-tracked the railway from Gebze to Arifiye. Tavşancıl station closed on 1 February 2012 and the platforms were demolished shortly after.

Altıntel Port ( Altıntel Tank ve Terminal İşletmeleri A.Ş.) is a tank terminal and port located in Kocaeli/GEBZE, Dilovası OSB Organized Industrial Zone of Turkey. It was established in 1987 for the storage of liquid chemical materials. Its primary customer is Arkem Chemicals, who started renting storage tanks in 1990's and took over the company in 2008.

Libyssa (Ancient Greek: Λίβυσσα) or Libysa (Λίβισσα), was a town on the north coast of the Sinus Astacenus in ancient Bithynia, on the road from Nicaea to Chalcedon. It was celebrated in antiquity as the place containing the tomb of the Carthaginian general Hannibal. In Pliny's time the town no longer existed, but the spot was noticed only because of the tumulus of Hannibal. The site of ancient Libyssa is located within the modern district of Gebze in Kocaeli Province, at the coast of the Gulf of İzmit, near the city of İzmit (ancient Nicomedia) in northwestern Anatolia, Turkey. Hannibal's monumental tomb in Gebze, Kocaeli, Turkey. Atatürk, the founding father of the Republic of Turkey, revered and admired Hannibal so much he honored him with a symbolic tomb close to where Hannibal had died.

Dilovası is a municipality and district of Kocaeli Province, Turkey. Its area is 125 km2, and its population is 53,416 (2022). The district Dilovası was created in 2008 from part of the district of Gebze, along with the districts Darıca and Çayırova. The mayor is Hamza Şayir (AKP).

Praenetus or Prainetos (Ancient Greek: Πραίνετος), also known as Prinetos or Prinetus (Πρίνετος) was a town of ancient Bithynia on the coast of the Propontis. It on the north side of Mount Arganthonius (Samanli Daği), and at the southern entrance of the Sinus Astacenus. It was situated 28 Roman miles to the northwest of Nicaea. Stephanus of Byzantium calls it Pronectus or Pronektos (Πρόνεκτος) and states that it was founded by the Phoenicians. If this be true, it would be a very ancient place, which can scarcely be conceived, as it is mentioned only by very late writers. According to Cedrenus it was destroyed by an earthquake. It was a bishopric; no longer the seat of a residential bishop, it remains a titular see of the Roman Catholic Church.Its site is located near Karamürsel, in Asiatic Turkey.

Karamürsel is a municipality and district of Kocaeli Province, Turkey. Its area is 262 km2, and its population is 59,676 (2022). It is on the south coast of the Gulf of İzmit. Before its conquest by the Ottomans it used to be called by the Greek name of Praenetos (Πραινετός in Greek). The modern name commemorates Kara Mürsel who founded the Ottoman navy and designed distinctive galley ships, called kadırgas, for it.Karamürsel holds special significance for the Turkish Navy, as it was here in 1323 that the Ottoman Empire first established an outlet to the sea, thus laying the foundations for the Ottoman Navy which would go on to dominate the eastern Mediterranean for several centuries. The Karamürsel area is not as heavily industrialised as other parts of Kocaeli province,. Ferry services link Karamürsel to İzmit and Hereke on the northern side of the Bay of İzmit.

Diliskelesi is a neighbourhood of the municipality and district of Dilovası, Kocaeli Province, Turkey. Its population is 10,910 (2022). It is a port on the north side of the Gulf of İzmit.

Diliskelesi railway station was a railway station in Diliskelesi, Turkey on the Istanbul-Ankara railway. It was located just southwest of Dilovası, in the southern part of the Diliskelesi in the industrialized port area. The station was a stop on the Adapazarı Express train service; 11 daily eastbound trains and 13 daily westbound trains stopped at Diliskelesi. The station was opened in 1975, when the Turkish State Railways double-tracked the railway from Gebze to Arifiye. Diliskelesi station closed on 1 February 2012 and the platforms were demolished shortly after.

The Osmangazi Bridge (Turkish: Osmangazi Köprüsü) is a suspension bridge spanning the Gulf of İzmit at its narrowest point, 2,620 m (8,600 ft). The bridge links the Turkish city of Gebze to the Yalova Province and carries the O-5 motorway across the gulf. The bridge was opened on 1 July 2016 to become the then-longest suspension bridge in Turkey and the fourth-longest (seventh-longest as of 2023) suspension bridge in the world by the length of its central span. The length of the bridge was surpassed by the Çanakkale 1915 Bridge across the Dardanelles strait, which became the longest suspension bridge in the world when it was opened on 18 March 2022.