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.

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.

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.

It's even more complicated. I grew up north east of Oslo, but speak close to western Oslo dialect with some now pretty-conservative Bokmål use (to the point where your rendition of Oslo-dialect is entirely different to how I speak - e.g. I prominently pronounce the "l" in "skal" and my pronunciation of "kirken" has nothing resembling any "sh-" sound), partly due to my dad, partly because I grew up reading a lot of old books.

At school we had an exchange student from Germany one year who quickly learnt to speak the local dialect, not too far from your rendition of Oslo dialect, but more -a endings, e.g. "kirka" rather than "kirken", but she struggled to understand me, because of those differences.

Those dialects are a 15 minute train ride apart.

People who grow up in Norway will understand multiple of these variants without necessarily being entirely aware of how different they can seem to foreigners, exacerbated by the fact we tone down the differences a lot in writing - in particular spoken Norwegian merges a lot of words. E.g. you can find people saying "skarru bli med?" ("are you coming?") while writing "skal du bli med?". But even those speaking forms of Norwegian close to conservative Bokmål like me while have pauses that are surprisingly short between some words - e.g. I have a gap between "bli" and "med" in my example sentence, but it's short enough that it's not a given it's clear for non-native speakers.

And despite the destigmatisation of dialect use in recent decades, a lot of the spoken Norwegian dialects that today deviate from both Nynorsk and Bokmål are rarely written down except in dialogue in novels, and even then it's politics - it's more common for more radical Norwegian writers to write dialogue in dialects (ironically, several of the most radical older Norwegian writers promoted Riksmål / conservative Bokmål - e.g. Arnulf Øverland was both a member of the communist Mot Dag - "Towards Dawn - and a president of the Riksmåls-association), making it even harder for foreign learners to get exposure to them during study.

To your issue of understanding people from Eastern Norway, in a reversal I still recall an embarrassing moment on holiday in Denmark as a child. I mostly understood spoken Danish (the article is polite and say they sound "blurred", while the old common joke is that Danish sounds like Norwegian spoken with a potato in your mouth), but at one point some kid was trying to talk to me at the beach, and I apologised to him, telling him I didn't understand his Danish very well.

That afternoon I learned my mum had talked to his parents, and the family was Norwegian, from Bergen, and most certainly not speaking Danish. I wouldn't mistake those two today, but he spoke differently enough to me that as a child guessing he spoke Danish was not a big leap.

I grew up in a Norwegian ex-pat community in Houston, Texas, attending the local Norwegian language church there. The priest would get rotated out every few years, and I remember as a kid being fascinated by the roulette wheel of "which dialect is the next priest they send going to speak?"

> Those dialects are a 15 minute train ride apart.

This prompts questions on the linguistic fallout of infrastructural development.

Presumably the train line is more direct and faster than any previous land (or sea) connection. In what year was the train line built ? And, how far apart in travel time were the dialects before then ? And, has there perhaps been an academic study of the effect over time of the train line on the relationship between the dialects ?

The train has been there since 1854 - it's along the oldest rail line on Norway.

It'd certainly have been a long trek before then (a day maybe?), but I think a lot of the distinction there is also socioeconomic - the West Oslo dialect is very much associated with the wealthiest part of town and the wealthy suburbs, and where there certainly were expectations around what was long seen as more cultured and educated language.

The line is actually very sharp in Oslo between the Eastern and Western parts of the city, and that initial gap is at least usually seen as socioeconomic , but the gap then gets even larger once you get further East and North.

Wow! You have preserved the dative case. "i kerken" instead of "i kerka". Dative is AFAIK not part of any standard Scandinavian language, but remains in some dialects. Steadily losing ground, though.

I don’t think it’s anything to do with case, just that the gender of the word is different between the dialects. ‘en’ or ‘a’ is just a suffix meaning ‘the’.

It is certainly possible that a word may differ in gender between dialects. But the way dative is normally expressed in Norwegian dialects is that masculine words get the normal feminine ending and feminine words get the masculine one.

Oh right, I didn’t know that! I still don’t imagine that’s what is happening in this case; there are just plenty more feminine nouns in Nynorsk and similar dialects.

I'm not sure about that particular dialect, if it's case or not, but it's a fact that some dialects do keep the dative (though it's been disappearing somewhat recently). In addition to certain country-wide expressions which have kept old case forms, like "gå mann av huse", and "i live" (being alive), though I've recently seen so-called "journalists" in newspapers being unable to understand it and writing "i livet" instead, which has a totally different meaning.