At that time, the leaders of the Central European countries decided to take joint action to identify new sources of modernisation for their economies, including in particular through better infrastructural integration of the region (the transport pillar), strengthening the security and competitiveness of its energy supply (the energy pillar), accelerating the development of the digital economy (the digital pillar), and thus strengthening the economic and social cohesion of the EU as a whole.

To date, eight 3SI summits have been organised – Central European presidents and leaders have met in Dubrovnik (2016), Warsaw (2017), Bucharest (2018), Ljubljana (2019), Tallinn (2020), Sofia (2021), Riga (2022) and again in Bucharest (2023). The next summit will take place on 11 April 2024 in Vilnius. The organisation of the 2025 summit has already been announced by Hungary.

1. The first 3SI Summit in Dubrovnik (25-26 August 2016) inaugurated the Three Seas format and attracted the attention of countries in the region and external partners interested in developing this new initiative (including, among others, global partners).
2. The second 3SI Summit in Warsaw (6-7 July 2017) brought strong political support from the United States, which recognised in the Three Seas an important and promising economic partner, especially in the area of energy. An expression of this support was the participation of US President Donald Trump at the Summit.
3. The third 3SI Summit in Bucharest (17-18 September 2018) brought concretisation of cooperation at the business level. The 3SI Business Forum was organised in Bucharest for the first time. During the summit, a letter of intent for the establishment of the 3SI Investment Fund was signed. The summit also resulted in a declaration of support from the European Commission for the priorities of this regional cooperation. US Secretary of Energy Rick Perry presented the concept of the Partnership for Transatlantic Energy Cooperation (P-TECC) during the Summit. Special guests at the Summit also included EC President Jean-Claude Juncker and German Foreign Minister Heiko Maas.
4. The fourth 3SI Summit in Ljubljana (5-6 June 2019) confirmed the formal registration of the 3SI Investment Fund, whose authorities included representatives of Polish, Romanian and Czech institutions. The summit was attended by, among others, the President of Germany, the President of the EC and the US Secretary of Energy. During the meeting, it was agreed that an annual report on the progress of priority projects would be presented at each summit.
5. The fifth 3SI Summit in Tallinn (19 October 2020) highlighted the importance of Three Seas cooperation in overcoming the negative effects of the COVID-19 pandemic in the region. The Estonian Presidency presented the concept of The Three Seas Smart Connectivity, envisaging the transformation of the Three Seas region into a global hotspot of e-mobility and energy innovation. The summit highlighted the significant strengthening of the Investment Fund (increase in Poland's contribution from EUR 500 million to EUR 750 million and declarations of accession to the Fund by Bulgaria, Croatia, Lithuania, Hungary and Slovenia).
6. The sixth 3SI Summit in Sofia (8-9 July 2021) brought closer scientific and educational cooperation. During the summit, investment agencies signed agreements on the creation of an innovation support network, while the chambers of commerce of the Three Seas countries signed their own cooperation network. Close cooperation at the level of national 3SI coordinators was declared in order to improve the implementation process of Three Seas projects. During Bulgaria's informal presidency, the parliamentary dimension of Three Seas cooperation was established to contribute to stronger legislative coordination among the 3SI member states. The summit was attended, among others, by Greek President Ekaterini Sakielaropulu and remotely by German President Frank-Walter Steinmeier and US Secretary of State Anthony Blinken.
7. The seventh 3SI Summit in Riga (20-21 June 2022) was the summit where the members of the Initiative decided to grant Ukraine the status of a participating state. An additional success of the summit was the declaration of the US International Development Finance Corporation to contribute USD 300 million to the 3SI Investment Fund. In addition to representatives of the US, Germany (President Frank-Walter Steinmeier) and the EC (Commissioner Valdis Dombrovskis), Ukrainian President Volodymyr Zelenski also attended the summit (in remote form). During the Latvian Summit, the 1st 3SI Civil Society Forum was organised, which inaugurated cooperation between civil society organisations operating in 3SI countries.
8. The eighth 3SI Summit in Bucharest (6-7 September 2023) was a summit attended, in addition to the 3SI participating countries, by representatives of the US, EC and Germany (strategic partners); Ukraine and Moldova (associate participating countries), as well as Italy, UK, Japan, Azerbaijan, Georgia, UAE and institutions such as the World Bank, International Monetary Fund, European Investment Bank, European Bank for Reconstruction and Development and the Organisation for Economic Cooperation and Development. The main provisions of the summit were the addition of Greece as the 13th participating state in the Initiative; the granting of an associated participating state status to Moldova (clarifying the analogous status for Ukraine, which had been granted associate status a year earlier at the Riga Summit); the completion of the fundraising phase of the first 3SI Investment Fund, which generated 5 projects with a total value of approximately EUR 6 billion; and the establishment of the Three Seas Business Development Association (TSBDA) to promote the interests of entrepreneurs and employers in the Three Seas region.

Priority projects submitted by Poland within the framework of the Three Seas Initiative

Starting with the 3rd 3SI Summit in Bucharest in 2018, 3SI participating countries have been submitting proposals for infrastructure projects aimed at better integrating the economies of the countries in the region. Projects are submitted under three main areas: transport, energy and digital. By the time of the last 3SI Summit in Bucharest, 93 priority projects had been submitted.

The most important projects from the point of view of Polish interests include:

Completed or partially completed projects:

• Diversification of gas supply and integration of gas infrastructure in the Three Seas region, including the completed Baltic Pipe pipeline, the commissioned gas interconnector with Slovakia, the ongoing expansion of the LNG terminal in Świnoujście, as well as the planned construction of a floating FSRU terminal in the Gulf of Gdańsk and an interconnector with Ukraine;
• Gas Interconnection Poland-Lithuania (GIPL) – the project, commissioned in May 2022, will connect the gas systems of Poland and Lithuania and, as a result, integrate the isolated gas markets of the Baltic States and Finland into the Polish and EU markets;
• Amber Rail Freight Corridor (RFC Amber) – the aim of the project was to establish a rail freight corridor between the Adriatic ports in Slovenia and Hungary, Slovakia and Poland. The project is fully operational as of 2019 and its participants are five railway entities: SŽ-I (Slovenia), GYSEV, MÁV, VPE (Hungary), ŽSR (Slovakia) and PLK (Poland). It is a freight project aimed at increasing the capacity of existing infrastructure rather than creating new infrastructure. The RFC is part of the EU-Ukraine Solidarity Lanes, a European Commission initiative to facilitate Ukrainian grain exports and trade between the EU and Ukraine.

Projects in progres:

• Baltic-Adriatic TEN-T Core Network Corridor – the project involves connecting major terminals (urban, port, airport and other transport terminals) through the development of rail, road, sea and air infrastructure between the Baltic and the Adriatic, i.e. Poland, the Czech Republic, Slovakia, Austria, Slovenia and Italy. The project is being developed as part of the EU's Trans-European Transport Network (TEN-T) programme;
• Improving railway connections between Polish cities and neighbouring countries – the aim of the project is to improve railway connections (mainly passenger transport) between Poland and the Czech Republic, Slovakia, Germany, Ukraine and potentially Romania. The nodal point of the project based on high-speed rail is to be located between Warsaw and Łódź (Centralny Port Komunikacyjny);
• Rail Baltica – the project was proposed by Poland and Lithuania, but Latvia and Estonia and – as an external partner – Finland are also participating). Rail Baltica comprises 840 km of new rail infrastructure in Lithuania, Latvia and Estonia and 370 km of upgraded rail infrastructure in Poland. Ultimately, the Polish section of Rail Baltica will be a double-track, electrified main railway line allowing a maximum permitted speed of over 200 km/h for passenger trains and 120 km/h for goods trains. This standard will also apply on the Lithuanian side. The project is in line with TEN-T and EU CEF (Connecting Europe Facility) regulations;
• Via Carpatia – the project has been proposed by Poland and also involves Bulgaria, Croatia, Lithuania, Hungary, Romania and Slovakia, as well as external partners: Greece, Turkey and Ukraine. Via Carpatia is included in the TEN-T key infrastructure. It is a North-South route connecting the Baltic, Black and Adriatic Seas, thus contributing to the overall improvement of the territorial and economic cohesion of the EU and the economic and social growth of Central and Southern Europe. The Polish section of the Via Carpatia will be completed in 2027. The entire main route is 712 km long, of which 259.6 km have been completed, 280.8 km are under construction and 171.6 km are under preparation and tendering procedures;
• Extension of the inland waterway link Poland-Czech Republic – the project was submitted by Poland, but the Czech Republic is also participating. It aims to build the missing element of the European inland waterway corridor. The missing link to the Czech Republic is an integral part of the Odra Waterway (E-30). The project will contribute to increasing the economic potential of the region;
• At the recent Bucharest Summit, Poland reported on a new priority project called Poseidon + HyFly2 proposed by ORLEN Group companies, which aims to connect future offshore wind farms on the territory of Lithuania, Latvia and Estonia by a transmission cable to the Mažeikiai Refinery in order to enable the latter to produce green hydrogen;
• The second new project submitted by Poland is the Centralny Port Komunikacyjny project for a high-speed rail link between Poland and Ukraine on the Warsaw – Lublin – Trawniki – Zamość – (PL/UA border) route with the possibility of an extension to Rawa Ruska and Lviv.

Three Seas Initiative Investment Fund

The Three Seas Initiative Investment Fund (3SIIF) was established in 2019 at the initiative of Poland and Romania. It is an instrument for financing joint projects, strengthening the practical dimension of the 3SI. The 3SIIF supports the financing of projects that create transport, energy and digital infrastructure in the Three Seas region. The shareholders of the Fund are Poland (after the Tallinn Summit in 2020, we increased our contribution to EUR 750 million), Romania, Estonia, Latvia, Hungary, Bulgaria, Lithuania, Croatia (each country pledged EUR 20 million) and Slovenia (pledged EUR 23 million). The countries that have joined the Fund are represented in the authorities of the institution (Poland is represented by Bank Gospodarstwa Krajowego). The 3SIIF operates under Luxembourg law, on a commercial basis, which means that investment decisions of the Fund's authorities are made based on the criterion of being able to generate a profit for shareholders. The Fund is managed by an independent entity, Amber Infrastructure Group. Based on commitments to date, the total value of the Fund has reached approximately EUR 923 million.

The US, following the Bucharest Summit in 2023, finalised a USD 300 million investment in the 3SIIF (in the form of a debt instrument).

With the majority of the Fund's accumulated funds invested in 5 investment projects (3SIIF's investment in 1-2 new projects is still tentatively announced), the decision has been taken to terminate the Fund's further fundraising from investors. The Fund will now focus on managing its portfolio of existing projects. The Fund does not disclose information on the amount of involvement in individual projects.

To date, the Fund has decided to fund five investment projects:

1. Acquisition of 100% of the shares in the Polish company Cargounit, the largest private locomotive leasing company, a leader in this field in Central Europe;
2. Investment in the Estonian company Greenergy Data Centers, which plans to build a network of green data centres in the Three Seas area;
3. Acquisition of shares in the Austrian company Enery Development GmbH, which deals with renewable energy production systems;
4. Purchase of shares in BMF Port Burgas EAD, the main port operator in the Port of Burgas in Bulgaria;
5. Investment in R.Power (the Fund will take a minority stake in the company for EUR 150 million), which is a leading independent power producer active in solar photovoltaics and battery energy storage. The company is based in Warsaw and has operations in Poland, Romania, Germany, Italy, Spain and Portugal.

In the declaration of the 8th 3SI Summit, there was encouragement to set up another investment fund. It is to focus on green-oriented infrastructure and renewable energy and digitalisation projects (excluding transport). Whether it can be established before the next 3SI Summit in Vilnius scheduled for 11 April 2024 remains to be seen.