That UK -- Norway link is (or was) the longest undersea electricity cable in the world[1] at 450 miles (720km).
How do the exports and imports balance; Finland is importing 800MW from Sweden then exporting 400MW to Estonia, is it possible some of that is the same power? Norway is importing 425MW from The Netherlands and exporting 1.2GW to the UK and 200MW to Denmark?
Why does the UK export 73MW to Northern Ireland but then import 286MW from the Republic of Ireland, i.e. why doesn't Northern Ireland import from Republic of Ireland and skip the overseas bit?
Keep in mind this is a very 'zoomed out' view of the power grid. In reality every country is going to have grid limits internally and different sources of demand in different places.
For example, in your Finland observation it may be cheaper/easier to supply the north of Finland from Sweden rather than send the power that could otherwise go to Estonia to the other side of the country, probably not a lot of north south distribution internally in Finland because of terrain (I know Norway really struggles with this, you can see huge price differences in the north of Norway vs south of Norway on EPEX Spot - https://www.epexspot.com/en/market-data), so I would assume Finland is the same.
The UK also has huge bottlenecks north/south in distributing power. There's 4GW of HVDC planned to transmit power from Scotland to England, for example. Probably much more is going to be needed: https://en.m.wikipedia.org/wiki/Eastern_HVDC
As it happens this has been in the news quite a bit, and we've been told that the Finnish trunk lines are built for this [1]. Finland isn't split up into multiple electricity price areas unlike its neighbors.
There is currently only one small interconnect between Ireland and Northern Ireland. Another one (1500MW) is being built. This will allow Northern Ireland to benefit from Ireland’s substantial wind resources (~2GW).
> Procurement for the supply of materials for the construction of the overhead line is underway. Testing of the final pylon designs is being undertaken, with a view to construction beginning next year in order to have the project fully operational by 2026.
How do the exports and imports balance; Finland is importing 800MW from Sweden then exporting 400MW to Estonia, is it possible some of that is the same power? Norway is importing 425MW from The Netherlands and exporting 1.2GW to the UK and 200MW to Denmark?
Why does the UK export 73MW to Northern Ireland but then import 286MW from the Republic of Ireland, i.e. why doesn't Northern Ireland import from Republic of Ireland and skip the overseas bit?
[1] https://www.bbc.co.uk/news/uk-england-tyne-58772572