The Baltic Sea is a large, shallow, brackish inland sea of the North Atlantic Ocean found in the northeastern part of the European continent. Bordered by Sweden, Finland, Denmark, Germany, Poland, Russia, and the three Baltic States (Estonia, Latvia and Lithuania), it is thinly connected to the North Sea through a series of Danish straits flowing around the Jutland peninsula and is home to four gulfs and an array of archipelagos. Due to its unique and centralized geography, the Baltic Sea has long played a critical role in seaborne trade, regional diplomacy and scientific research.
The Baltic Sea’s geography is not only expansive but unique. With an area of around 377,000 km², it is the second largest inland sea in the world, only coming in second to the Mediterranean Sea. Due to its large inflow of freshwater from its massive catchment area—the area from which the sea gets its water, which in this case is four times the size of the sea itself—and its lethargic exchange of water with the North Sea and the Atlantic Ocean beyond due to differing densities, its salinity remains considerably low, making the Baltic Sea arguably the largest body of brackish water in the world. Furthermore, though its deepest point is about 460 meters, its average depth is only 54 meters; a depth that is considered extremely shallow compared to its peers. It also contains several largest hypoxic (low-oxygen) areas, both natural and human-made. This variety makes it a keen body of interest and importance for environmentalists and scientists alike who work to study—or protect—the sea’s wide array of sea life.
Its breadth and central location also made it a historically vital trade route, dating back to the medieval period and it remains one of the busiest seas today. The man-made Kiel Canal—finished in 1895 but supposedly theorized since the 7th century—that cuts across the now-German state of Schleswig-Holstein now allows ships to avoid encircling Denmark’s Jutland to reach the North Sea, further easing trade with the inland sea.
Today, the Baltic Sea remains a core of European trade and institutional importance, especially with the extensive installation of submarine cables now fuelling communication and power in the region. As naval power and regional instabilities are surging, regional parties are increasingly concerned about Baltic Sea security and looking to prevent conflict before it arises, breeding an uptick in maritime naval exercises and legal protections. In 1992, the Council of the Baltic Sea States and its rotating presidency was established to help regulate and address governance of the Baltic Sea.
The Baltic Sea is witness to a myriad of events and intrigue, especially as of late. In April, archeologists identified what they believe may be Europe’s oldest human-made megastructure, from the Palaeolithic era, located 21 meters below the surface of the Bay of Mecklenburg, Germany. Similarly, researchers are again contemplating how coins from the Roman Empire landed on a remote island in the Baltic Sea, analyzing how sacrificial horses crossed the Baltic Sea during the Late Viking Age, and finally announcing after 13 years of study that a mysterious, oddly-shaped structure lying 90 meters underwater is likely a natural phenomenon.
Simultaneously, scientists and observers have been paying heavy attention to the Baltic Sea’s toxic thallium levels, which a new study finds is dominantly human-wrought and have “fundamentally changed the chemistry of the Baltic Sea.” These findings of increased thallium—a metal toxic to mammals and marine ecosystems—has already brought reprimand upon regional industrial and wartime activities from the 1940s to the present and can be expected to continue. Other environmental battles have been brought to light in the last month: debates on the economically sound scrubber systems on ships that large volumes of pollutant; the slow extinction of Baltic herring and its link to Norwegian salmon; new examinations of the interplay between groundwater emissions and Baltic Sea pollution; and the recovery of tens of thousands of tonnes of chemical weapons, munitions and unexploded bombs dumped into the Black Sea. Positive battles towards sustainability are also highlighted, such as the installation of the Baltic Sea’s largest wind farm and a fresh effort by two ports in Sweden and Finland to cut port waiting times, which thus reduces fuel consumption and carbon emissions.
Even more pressing to most is the Baltic Sea’s role in regional security as it pertains to Russia. In mid-May, the Russian Defense Ministry released a draft government decree unilaterally proposing a change to Russia’s maritime borders with Lithuania and Finland in the Baltic Sea; a release that was deleted from the official document portal on May 22 and has since been denied by authorities. Not long before, Lithuanian intelligence released a report describing Russian military plans of a standoff with NATO nations in the Baltic Sea region lasting “at least several years.” Estonia’s defense commander proposed blockading the Baltic Sea to reduce options for aggressors as broader concerns of an escalation into direct NATO country involvement in the Ukraine conflict still hover. Russia is also being linked to several cases of electronic warfare over the Baltic Sea, applying mass GPS jamming across northern Europe and impacting both commercial and military aircraft.
The Baltic Sea will inevitably remain relevant in global maritime affairs, especially when it comes to the geopolitics of NATO states and the West’s relations with Russia. While there is much recent talk centered around sustainability and climate preservation—perhaps linked to the European Union’s commemoration of the 50 year anniversary of the signing of the Helsinki Convention, which was primarily established by Baltic Sea coastal states to defend the region’s marine environment—the security narrative should be expected to take precedence at the multinational level. Regardless, climate activists, scientists and even treasure hunters will continue to value this body of water’s unique properties and historic significance.
Most notably, with Sweden’s ascension to NATO member country status in March 2024, all coastal states of the Baltic Sea—excluding Russia—are now NATO member countries. Increased NATO security talks, workshops and naval exercises in the Baltic Sea are inevitable for the future, with the newly revived, annual Estonian Navy-led operation Open Spirit 2024 and the Iceland-based, multinational anti-submarine and anti-surface warfare exercise Dynamic Mongoose 24 being two examples. Russia’s Baltic Sea coastline is admittedly short, but that does not detract from its threat level, especially with St. Petersburg—Russia’s second-largest city—sitting on that coast and talks of nuclear weapons hovering over every conversation. So long as the Ukraine-Russia conflict continues and fears of Russia’s nuclear—or other destabilizing—activities persist, the Baltic Sea will need to remain a place of vigilant defense.
This Spotlight was originally released with Volume 3, Issue 5 of the ICAS MAP Handbill, published on May 28, 2024.
This issue’s Spotlight was written by Jessica Martin, ICAS Research Associate & Chief Editor, ICAS Newsletters.
Maritime Affairs Program Spotlights are a short-form written background and analysis of a specific issue related to maritime affairs, which changes with each issue. The goal of the Spotlight is to help our readers quickly and accurately understand the basic background of a vital topic in maritime affairs and how that topic relates to ongoing developments today.
There is a new Spotlight released with each issue of the ICAS Maritime Affairs Program (MAP) Handbill – a regular newsletter released the last Tuesday of every month that highlights the major news stories, research products, analyses, and events occurring in or with regard to the global maritime domain during the past month.
ICAS Maritime Affairs Handbill (online ISSN 2837-3901, print ISSN 2837-3871) is published the last Tuesday of the month throughout the year at 1919 M St NW, Suite 310, Washington, DC 20036.
The online version of ICAS Maritime Affairs Handbill can be found at chinaus-icas.org/icas-maritime-affairs-program/map-handbill/.
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