Lake Saimaa is the largest lake in Finland and one of the largest in Europe, a vast interconnected network of channels, bays, and islands covering nearly 4,400 square kilometres. Boat trips from Lappeenranta harbour range from 90-minute sightseeing cruises around the nearby islands to longer excursions into the lake's interior, including overnight trips to Savonlinna and its famous Olavinlinna castle.
Day cruises along the Saimaa Canal to Vyborg have historically offered a route through Russian Karelia to the medieval city of Vyborg — an extraordinary journey given the political history of the region — though availability depends on the current state of Finnish-Russian relations. The summer season runs from June through August; boats are infrequent outside these months.