The only airport in the region is at Savonlinna, which has service to Helsinki.
By train
By train
South Savonia's major cities are all well-served by rail, although you may need to change trains in Kouvola. It's 3 hours from Helsinki to Savonlinna or Mikkeli, or about 4 hours to Pieksämäki. There's also a cross line from Turku, Tampere and Jyväskylä to Pieksämäki.