Suurisuo is a largely natural bog area around 100 hectares in size, whose rocky forest islets and pools increase its landscape value. As is typical for raised bogs, Suurisuo’s vegetation is rather barren and consists of ten types of pine bogs and a few types of poor fen. The flora contains no endangered or rare species of plant, but all species that are typical to the mire types are represented. The area used to be part of the Southern Saimaa ice lake, and there is a sandy formation to the northeast of the bog that is interpreted as a delta.