Major towns on the lakeshore include Lappeenranta, Imatra, Savonlinna, Mikkeli, Varkaus, and Joensuu.

About 6,000 years ago, ancient Lake Saimaa, estimated to cover nearly 9,000 km2 (3,500 sq mi) at the time, was abruptly discharged through a new outlet.

Saimaa exhibits all major types of lake in Finland at different levels of eutrophication.

[6] Due to its rich, easily accessible asbestos deposits, the shores of the lake are the most probable origin of asbestos-ceramic, a type of pottery made between c. 1900 BC – 200 AD.

Other canals connect Saimaa to smaller lakes in Eastern Finland and form a network of waterways.