The wonderful pink granite of the Åland Islands worn smooth by glaciers millions of years ago but still vibrant today with that wonderful line of green algae. The card is one by the Posten Åland and at first I didn't notice that down the divide it said it was of "natural environment of Åland, Föglö" Of course once I saw that I knew we were talking stamps here and off I went to The Top of The World site and found the answer. This is one of the series of scenery stamps issued over a number of years by the Åland post.
"With its 600 inhabitants Föglö is the largest archipelago municipality in Åland. In summer the population increases almost threefold when some 600 summer cottages come alive....Kjell Söderlund took the photo from Algersö, Föglö, showing a rock by the sea, smooth as a mirror"
It sounds a wonderful place to spend a summer for there are hiking and cycling trails and of course sea paddling where one could glide round these rocks.