Heinola in the context of Asikkala

Speleology (from Ancient Greek σπήλαιον (spḗlaion) 'cave' and -λογία (-logía) 'study of') is the scientific study of caves and other karst features, as well as their composition, structure, physical properties, history, ecology, and the processes by which they form (speleogenesis) and change over time (speleomorphology). The term speleology is also sometimes applied to the recreational activity of exploring caves, but this is more properly known as caving, potholing (British English), or spelunking (United States and Canadian English). Speleology and caving are often connected, as the physical skills required for in situ study are the same.

Speleology is a cross-disciplinary field that combines the knowledge of chemistry, biology, geology, physics, meteorology, and cartography to develop portraits of caves as complex, evolving systems.

Kymijoki (Swedish: Kymmene älv) 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.

Being one of the largest rivers in Southern Finland, Kymijoki 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.

Lahti (Finnish pronunciation: [ˈlɑhti], lit. 'bay'; Swedish: Lahtis) is a city in Finland and the regional capital of Päijät-Häme. It is located in the Finnish Lakeland. The population of Lahti is approximately 122,000, while the sub-region has a population of approximately 205,000. It is the 9th most populous municipality in Finland, and the sixth most populous urban area in the country.

Lahti is situated on a bay at the southern end of lake Vesijärvi about 100 kilometres (60 mi) north-east of the capital city Helsinki, 38 kilometres (24 mi) south-west of Heinola and 74 kilometres (46 mi) east of Hämeenlinna, the capital of the region of Kanta-Häme. Lahti is situated at the intersection of Highway 4 (between Helsinki and Jyväskylä) and Highway 12 (between Tampere and Kouvola), which are the most significant main roads of Lahti. Its neighboring municipalities are Asikkala, Heinola, Hollola, Iitti and Orimattila.