[larsiusprime]

For context, my elderly mother grew up in a coastal village that was inaccessible to the rest of the country except by boat! (A tunnel has long since been dynamited through the mountain and the village is now well connected with the rest of the country)

There's an entire coastal dialect that runs up and down parts of the country where those people's dialect is closer to each other's than it is to their neighbors just a few miles inland.

[Tor3]

Yep. Living near the sea means access. In three weeks you could go all the way from Bergen to Lofoten by sail. As soon as you set foot on land.. no access. Before roads and tunnels. Even recently.. the book "Three in Norway, by two of them" from 1881 was written by a couple of British guys (they were three, but two wrote the book) going to Jotunheimen for fishing and hunting. They left by ship from Newcastle and arrived in Oslo (today's name) after just two days, but going from Oslo to (at the map, "nearby") Lillehammer took three whole weeks. With support from locals and guides and there was even a road at the time.

My grandfather, who lived at the coast, could meet people up and down the coastline as much as he wished. But there could be people living just a few kilometers away, as the crow flies, who he would never meet.. because there was a mountain in between.

Thus, dialects along the coast have much more in common with each other for much longer distances than inland dialects which can vary greatly even over relatively short distances.

[vidarh]

A lot of my genealogy is significantly helped by considering if possible ancestors were in plausible walking vs. boating distance. You then need to prove connections, of course, but quickly ruling candidates out because they'd have lived days of walking through mountains apart even though it "looks close" today has saved a lot of wasted time.