Kesämaa is a seasonal family activity park in Punkaharju, with water slides, pools, games, and outdoor play in the lake-and-ridge landscape. It is aimed squarely at families rather than sightseers chasing heritage or scenery.
That said, it fills a real gap on a summer trip through the Finnish Lakeland. Use it as a warm-weather half-day if you are travelling with children and want a break from museums, viewpoints, and forest walks.