The average age of the pine forests are 75-100 years of age. Old forests are very few. The oldest pine forest in the National Park can be found in the middle part of Virmailansaari. On the esker islands the landscape is dominated by heaths covered with well spaced Scots pines. The groves of the upper slopes and esker summits standing on poor dry mineral soil are the specialties of the flora on Kelvenne island.
Groves cover about one-tenth of the surface area.
There are about 70 km of shoreline in the parks islands. Going ashore and moving about is forbidden during the snowless period in several of the sandy beach areas to protect the fragile vegetation and hopefully to help it restore itself naturally. During the years 1992-1993 an account of nearly 300 vascular plants was made in the National park. None of the nation-wide endangered species of plants were found in the park. In the 1960's, a plan was made to build up the Kelvenne esker island as a holiday resort with a casino, monastery, zoo, heated pond, shopping center and so forth.