I agree that one spot on dry ground can have more than one name, like Vancouver in Metro Vancouver Regional District in British Columbia. The same is the case for bodies of freshwater, completely surrounded by land, such as Lake Huron and its component known as Georgian Bay. But with seawater, it is not as clear-cut, and this same kind of relationship is very much open to interpretation.

Well, as you can see, Jarek, I have abruptly stopped this project in its tracks just short of Halifax because of the blowback I have received in response. I did add a tag to all of these relations to allow editors to easily filter them out if they want no part of them while they are editing coastlines, in response to the ensuing discussion I took part in on the talk-ca list, and I am perfectly fine with people breaking these relations if they want to do coastline edits, as long as I make regular trips to OSM Inspector to see which such relations have been broken, so I can repair them. As I have said earlier, I am willing to maintain this data myself. However, this project gave me something with which to occupy my time, and I would really be grateful to at least be allowed to continue with it.

“any future edit to any part of the coastline will create a new version of those giant polygons you are creating”

But isn’t that what is already happening with all the other big polygons imported from CanVec, like woodland data?

I fail to see how these relations would be unmaintainable, given there are tools to help with such maintenance, such as OSM Inspector. Plus, the JOSM validator recommends to define bodies of water as areas instead of just points, and I have been taking steps to preserve the integrity of the existing OSM data.

Besides, personally, this is another way for me to express my patriotism for the country I was born in and have lived in all my life.

The official coordinates would need to be integrated into all of the relations that follow that boundary, such as the boroughs of Alaska and the Regional Districts of BC.