The "Map of European Transmission System Operators" at the top of this page shows relevant geographical context: https://en.wikipedia.org/wiki/Synchronous_grid

The "Map of European Transmission System Operators" at the top of this page shows relevant geographical context: https://en.wikipedia.org/wiki/Synchronous_grid_of_Continental_Europe https://en.wikipedia.org/wiki/Synchronous_grid_of_Continenta... Note how Denmark is split between two separate synchronous grids. There are lots of high-voltage DC connections between the grids in this map.