Kymenlaakso is a region in Finland. It borders the regions of Uusimaa, Päijät-Häme, South Savo and South Karelia and Russia. Its name means literally The Valley of River Kymi. Kymijoki is one of the biggest rivers in Finland with a drainage basin with 11% of the area of Finland. The city of Kotka with 51,000 inhabitants is located at the delta of River Kymi and has the most important import harbour in Finland. Other cities are Kouvola further in the inland which has after a municipal merger 81,000 inhabitants and the old bastion town Hamina.

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. The name of the river, itself, kymi, means "large river", in Old Finnish.