FSX needs to add seaplane bases in the UK, throughout the Baltic and along the Norwegian coast. Before returning to the UK I live a number of year in Canada. Loads of actual seaplane bases along all three coasts and inland waters, of which many are available in FSX.
There use to be (real) bases in Scotland (Tobermoray and Oban) and there are actual seaplane base currently in Glasgow and Loch Lomond but FSX doesn't show them. I cannot find Scenery downloads anywhere for bases and facilities except for Canada, USA and the Caribbean, unfortunately. There are lots of places to land in the UK and Ireland but no docking facilities.
Whether it's the J3 cub on floats, the Twin Otter (Viking) DHC-6 float plane, or the Empire Airways flying boats, who else shares the joy and skills required to fly seaplanes/amphibians?