The Kymi is a river in Finland. It begins at Lake Päijänne, flows through the provinces of Päijänne Tavastia, Uusimaa and Kymenlaakso, and discharges into the Gulf of Finland. The river passes the towns of Heinola and Kouvola. The town of Kotka is located on the river delta.
The length of the river is 204 kilometres (127 mi), but its drainage basin of 37,107 square kilometres (14,327 sq mi) extends to almost 600 kilometres (370 mi) inside the Tavastia, Central Finland, Savonia and Ostrobothnia.
The furthest source of the river is Lake Pielavesi, its furthest point being some 570 kilometres (350 mi) from the sea measured by flow route.
Being one of the largest rivers in Southern Finland, the Kymi is a major source of hydroelectricity. The towns of Kotka, Kuusankoski, Myllykoski and Inkeroinen along the river are major centres of the pulp and paper industry. Formerly the river was extensively used for timber rafting.
The Kymijoki river has five mouths. It divides into two main branches near the Kultaankoski rapids in Kotka, about 15 kilometres (9 mi) inland of the Gulf of Finland. The eastern branch splits into the Korkeakoski and Koivukoski branches, the latter branch dividing again to form two mouths (Langinkoski and Huumanhaara). The Korkeakoski branch has only one river mouth.
The western branch divides into Ahvenkoski and Klåsarö branches, each with one mouth.
The westernmost Ahvenkoski branch of the river served as a border between Sweden and Russia from 1743 to 1809. The parts of Finland east of the river were later called Old Finland. Old Finland was incorporated in the Grand Duchy of Finland in 1812.
The Kymi is very swift: it takes three days for its waters to run from lake Pyhäjärvi to sea. Its mean depth is 9 metres (30 ft), and the deepest place is 29 metres (95 ft).
