From 23 to 25 September 2025, POP3 experts participated in person and virtually in the CASTIEL 2 All-Hands Meeting (AHM) in Tallinn, Estonia. The AHM brings together the National Competence Centres (NCCs) and HPC Centres of Excellence (CoEs). During the three-day event, participants reflected on achievements, discussed challenges and explored ways to shape the future of HPC collaboration in Europe. A key topic of discussion was how to increase the visibility of HPC across Europe and make the technology more accessible to industry, academia and public administration. The agenda also featured dedicated poster sessions, where POP3 was represented alongside other CoEs such as dealii-X, ChEESE-2P, HIDALGO2, and EXCELLERAT P2.

For POP3, the AHM proved particularly effective in facilitating connections with colleagues from other CoEs and NCCs. Conversations highlighted shared challenges, such as knowledge transfer to industry, training needs and clear communication within and across projects. We also learned that perceptions (and knowledge) of CoEs by NCCs vary widely. Finally, we used the meeting for discussions with representatives from several NCCs to encourage them to promote POP3 services.

The Tallinn meeting reaffirmed that collaboration between NCCs, CoEs and related initiatives is vital for fostering innovation and knowledge exchange.