For ocean model applications that require explicit simulation of eddy activity the Rossby radius of deformation is a parameter that determines a necessary model resolution. Unstructured mesh models allow the construction of meshes that change the resolution according to the Rossby radius. We discuss FESOM2 performance on meshes that globally have resolutions of up to 4 points per Rossby radius and regional simulations down to 1 km scale. We will show the results of the analysis of the main computational kernels with a special focus on bottlenecks in parallel scalability. We will discuss challenges and solutions related to the handling of the huge amount of data produced by a model setup with very high resolutions.
