NORDUnet operates a world-class network supplying connectivity between the national research and education networks (NRENs) of the five Nordic countries. More than 400 research and education institutions in the Nordics, with over 1.2 million users, are connected. The NORDUnet network is based on high-speed, high-capacity fiber links and spectrum sharing. Building the network is a never-ending process. Large-scale research facilities produce still heavier data sets, while international scientific collaborations become ever more active.