Kocaeli Province (Turkish: Kocaeli ili, pronounced [kodʒaˈeli]) is a province of Turkey. Its capital is İzmit, which is sometimes referred to as Kocaeli itself. The largest towns in the province is now İzmit and Gebze. The traffic code is 41. The province is located at the easternmost end of the Marmara Sea, especially on the Gulf of İzmit. Because of the size and natural conditions of the Bay of İzmit, the city is a giant natural harbour. Bordered to the east city of Istanbul. In 1888 the city is divided into Istanbul. There are lots of harbour facilities within Kocaeli, including the primary base of the Turkish Navy. The title of the city is the industrial capital of Turkey. The city has an airport named Cengiz Topel Naval Air Station. This airport is used by the air forces of both civilian transport. City has two universities; Kocaeli University and Gebze Institute of Technology.(Wikipedia) 

Kocaeli, more commonly referred to as Izmit, is located in the Kocaeli Province of Turkey's Marmara region. Situated in the Gulf of Izmit, it is 100 km from the metropolis of Istanbul. The city is unusual as it is built in two parts; with the centre of the city on a flat plain and the rest of the city on the hillside.

Historically the city was known as Nicomedia, which was a prominent capital city of the Roman Empire (286-324). The city's prominence continued under the occupation of the Byzantines, Seljuks and Ottomans. Even in modern times it is an important industrial, transportation and communication centre.

If you venture through the hillside portion of the city you will see traditional houses, built using Ottoman architecture. These houses give you insight into the lifestyle of the city's previous inhabitants. There are also a number of historic sites you can visit within the city and the surrounding area. You can visit the Temple of Augustus, the agora, the Byzantine fortress, the Orhan Gazi Mosque (dating from 1333), the amphitheatre, the nymphaeum, the Demeter Temple, the Uctepeler Mound King Tombs, the 16th century Mehmed Bey Hamam (Turkish bath), the Pertev Pasa Fountain and much more.

When in Kocaeli (Izmit) you should try the traditional Turkish sweet Pismaniye, for which this region is renowned.

There are a number of hotels in the city providing accommodation facilities. These range from small affordable hotels to upscale hotels and spas.

If you are arriving by flight the nearest airports are Sabiha Gokcen (45 km away) and Ataturk International (80 km away) in Istanbul. You can also reach Kocaeli by national bus service into the main bus terminal (otogar).