Mustikkamaa

This guide to Mustikkamaa, a wooded island park off Helsinki's harbor, uncovers what sits beneath its blueberry heath: three rock caverns blasted out of granite in the 1980s to hold Cold War era emergency oil reserves. You'll hear how the city's energy company Helen later found a different use for the same hollow rock, and what that says about a small recreational island hiding infrastructure under the joggers and blueberry bushes above. Look closely at the pink granite underfoot, scored smooth by glaciers thousands of years ago.