Basic information

The Three Seas Initiative (3SI, TSI)

The Three Seas Initiative, also known as the Three Seas, is a collaborative project to improve connectivity between the northern and southern regions of the eastern parts of the European Union (EU). The 3SI declarations, adopted annually at 3SI presidential summits, serve as the fundamental documents defining this format. The 3SI’s main priorities include the development of infrastructure within the areas of transport, energy, and digitalization.

The presidents of Poland and Croatia first proposed the idea to establish the 3SI, which was subsequently developed in collaboration with other states, with Romania being actively involved. The inaugural 3SI summit was held in Dubrovnik in 2016 and originally included 12 EU member states. Greece joined the 3SI in 2023, bringing the total number of participating states to 13. These states are EU members, including Austria, Bulgaria, Croatia, Czech Republic, Estonia, Greece, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia, and Slovenia. According to the Bucharest 3SI declaration (2023), the 3SI has three strategic partners: the European Commission, the United States of America, and the Federal Republic of Germany. Ukraine and Moldova are also associated participating states in the 3SI.

The main objective for initiating this collaboration was to bolster the economy of Central Europe. It is imperative to build infrastructure links that go beyond individual states’ efforts. Thus, there is a need for concerted efforts to improve connectivity between the northern and southern regions of the European Union.

The organizational model of the Three Seas Initiative is based on annual summits (summit diplomacy), where joint declarations are adopted. The organizing state’s president convenes the summits. Croatia (2016), Poland (2017), Romania (2019 and 2023), Slovenia (2019), Estonia (2020), Bulgaria (2021), and Latvia (2022) have hosted the summits so far. The 2024 3SI summit is scheduled to take place in Vilnius in April, with Budapest hosting the event in 2025.

The 3SI is defined by its participants as “a flexible Presidential Forum that provides political support to foster a more effective cooperation of governments, business entities, and non-governmental organizations interested in boosting regional bonds while recognizing that achieving concrete results within this Initiative requires an active involvement of the respective governments and working contacts among respective Presidential representations” (from the 2017 declaration).

The official website of the Three Seas Initiative

“Państwa Inicjatywy Trójmorza”/”Three Sea Initiative states”

An article by Paweł Nierada, First Vice President of the Management Board of BGK concerning the Three Seas Investment Fund