Tallinn, Estonia

For the past ten days we have explored from one side of the Baltic to the other, crisscrossing the sea in the path of Vikings, grand navies and rich merchant vessels loaded with cargos of salt and spice, wood and wool, amber and ivory. In Tallinn, the thousand-year-old capital of Estonia, all this history seemed to flow together as we explored the churches and fortress of the Teutonic Knights, the merchant town of the Hanseatic League and the modern city, once squabbled over by armies from east and west, now thriving as a center of transportation and commerce.

All the histories of the Baltic, all its many peoples and all the nations that share its shores are knit together by the sea itself. It is a unique body of water. Connected to the North Sea only by narrow straits, it has been isolated from the sea as a lake more than once in the recent past and today is only about one third as salty as normal seawater. This brackish nature makes it a difficult place for many marine species to survive. Nevertheless, important fisheries for cod, herring and other species play a vital role in story of the Baltic, and, particularly in the southern and western regions, a robust ecosystem of small fish, invertebrates and macro algae thrives along its rocky shores.

Low salinity is also key to the tremendous importance of the Baltic as a site for marine archeology. Because Teredo navalis shipworms cannot thrive here, wooden shipwrecks survive far longer in these waters than in most other seas. Recent surveys have found the relatively shallow floor of this inland sea to be littered with thousands of wrecks, each one of them another window into the culture and history of the region. Again there seemed to be a marvelous convergence of this history with our experiences of the day, this time coming together from above and below the sea, as we visited the beautiful four-masted barque Pommern in Mariehamn yesterday and then today saw video from a dive on the wreck of the Plus, a three-masted barque from the same era and the same shipping company, entombed in the dark green waters of Åland for almost eighty years.

This is the very soul of an expedition to the northern Europe, the essence of the style that sets us apart from a cruise through the same area. By using the technology of the National Geographic Explorer to look beneath the surface of the Baltic, we have been able to explore both the biology and the history of this unusual sea, thereby adding another layer to our experience of the long, rich and ongoing story of the beautiful region that surrounds it.