Bogs and other wetlands make up roughly 18,100 hectares (45,000 acres) or 48% of the former municipality's area, the average in Central Finland being 25%.

The largest wetlands are Kivisuo, Haapasuo, Havusuo, Rokasuo and Höystösensuo.

[2] Leivonmäki has fewer lakes than the Central Finnish average as it is located on a drainage divide area within the Kymijoki basin.

According to Väinö Voionmaa, Leivonmäki may also have been named after the Leivonen farm in the village of Anajala in Sääksmäki.

[6] The initial element is most likely the word leivo "skylark", though linguist Terho Itkonen also considered the possibility of the dialectal variant Levonmäki being the original form of the name.