Five European capitals await on this tour of the Baltic’s treasures. The stately cities of this strategic sea have long prospered from trade, giving rise to landmarks like Copenhagen’s colorful Nyhavn waterfront. Yet the sea also brought dangers, as evidenced by imposing fortifications, like Tallinn’s old town. Explore Gdańsk to learn of Baltic amber, and stroll cobblestone streets on the “Sunshine Island.” A touch of Scandinavian cool rounds out this voyage.