Sefine Shipyard

Helenopolis (Greek: Ἑλενόπολις) or Drepana (Δρέπανα) or Drepanon (Δρέπανον) was an ancient Greco-Roman and Byzantine town in Bithynia, Asia Minor, on the southern side of the Gulf of Astacus. It has been identified with the modern village of Hersek, in the district of Altınova, Yalova Province. It is traditionally considered as the birthplace of Saint Helena.

Limnae or Limnai (Ancient Greek: Λίμναι) was a town of ancient Bithynia on the coast of the Propontis. It was a colony of Miletus.Its site is located near Hersek, in Asiatic Turkey.

Hersek headland (Turkish: Hersek burnu) is a headland in Turkey.

Boğaziçi Shipyard (Turkish: Boğaziçi Tersanesi) is a Turkish shipyard established in Kadikoy, Istanbul, in 1992. The company's head office located in Istanbul, Turkey, new shipbuilding facilities located in Yalova Turkey.

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.

Subaşı is a town (belde) in the Altınova District, Yalova Province, Turkey. Its population is 8,281 (2022). It is close to Hersek Headland of Marmara Sea and has almost merged to Altınova to the east. The distance to Yalova is 12 kilometres (7.5 mi). The name of the village refers to subaşi, a title in the Ottoman bureaucracy and the residents of the town are mostly Turkish, Tatar and Gagauz migrants who left Dobrudzha and Deliorman area in Romania today Bulgaria around 1935. The settlement was declared a seat of township in 1992. It suffered severely in the 7.6 magnitude 1999 İzmit earthquake.

Altınova is a town in Yalova Province in the east of Marmara region of Turkey. It is the seat of Altınova District. Its population is 9,042 (2022). The mayor is Metin Oral (AK Party).

Beșiktaș Shipyard (Turkish: Beșiktaș Tersanesi) is a Turkish shipyard established in Altınova, Yalova in 2007.

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.

Altınova District is a district of the Yalova Province of Turkey. Its seat is the town of Altınova. Its area is 113 km2, and its population is 32,207 (2022).

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.

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.