Kotka is a town in the southern part of Kymenlaakso County on the shores of the Gulf of Finland. Kotka is a major port and industrial city and also a diverse school and cultural city. The city has a population of 51,889 (June 30, 2020). Kotka's neighboring municipalities are Hamina, Kouvola and Pyhtää. In the regional division, Kotka belongs to the Kotka – Hamina region.

The history of Kotka is related to the history of its mother, Kymi. The chapel of Kyminkartano, which belonged to Pyhtää, was built around 1440. The parish of Kymi became independent in 1642. With the urbanization, the city of Kotka was first separated from Kym in 1879 and the township of Karhula in 1951. In 1977.

The center of Kotka is located on Kotkansaari. Another important center is the former church village of Kymi parish and the center of the Karhula town, which now belongs to the Karhula and Helilä districts. The most significant apartment building suburbs are Karhuvuori in the west and Sunila in the east. Kotka's city center is divided into town districts. Outside the city center, there are mostly rural, unplanned villages. Kotka has a land area of ​​277.77 square kilometers, of which 5.82 square kilometers are inland waterways. The sea area is 671.99 square kilometers. The cityscape of Kotka is characterized by the broken coast of the Gulf of Finland with its archipelagos and the mouths of the Kymijoki River. The largest of the islands are Mussalo, Kirkonmaa, Kuutsalo and Kotkansaari. The outer archipelago of the Gulf of Finland is the Haapasaari archipelago. Hovinsaari and Kolkansaari are peninsulas protruding into the sea between the mouths of the Kymijoki River, which can also be considered as islands, as the Kymijoki River separates them from the mainland.

The Kymijoki river flows into the sea as three branches in the city area, from west to east listed Langinkoskenhaara, Huumanhaara and Korkeakoskenhaara. Hovinsaari lies between Langinkoski and Huumanhaara and Kolkansaari between Huuman- and Korkeakoskenhaara. There are several rapids in the Kymijoki area in the Kotka area. The largest free-flowing rapids are Pernoonkoski, Langinkoski, Siikakoski and Kultaankoski. Hydropower plants have been built in Korkeakoski and Koivukoski.

There are only two small lakes in Kotka, about one kilometer in diameter, and some ponds about 300 meters in diameter. Lake Laajakoskenjärvi next to the Pernoonhaara of the Kymijoki River was originally a river cove. As a result of the clearing and straightening of Laajakoski and the consequent lowering of the water level, it is now separated from the river by a narrow tributary. Lake Rapakivenjärvi on the border of Kotka and Kouvola is an almost overgrown lake, located along the branch of the ancient Kymijoki River that led to the present Nummenjoki River. Laajakoskenjärvi and Rapakivenjärvi belong to Natura 2000 areas.

The highest point of Kotka is Suurivuori, located near the Hamina border, at an altitude of 87 meters above sea level. Other high points are the Kymi airport area (about 72 meters) and Pernoon Haukkavuori (69.1 meters). The bedrock is mostly rapa rock. On the east side of the Kymijoki River there is a partly intermittent longitudinal ridge. Along the Kymijoki and Nummenjoki rivers there is flat clay and former marshes that have been cleared into fields. The most significant of the natural marshlands is Mustanjärvensuo, located near the border with Pyhtää, which belongs to Valkmusa National Park.

The climate is particularly affected by the Gulf of Finland near the coast, as a result of which the southern parts of the city have features of a maritime climate. In the northern parts of the city, the climate is already much more continental.