I speak no Scandinavian languages and am not any kind of expert on them. I have been told the following, which I found interesting, and wonder (a) if it is true and (b) what people think about it. I haven't Googled anything, just putting this out to try it.
A man from Oslo is married to a Dane. She speaks Danish to him and he replies in Norwegian and vice versa. The language spoken in the Oslo area is a sort of Danish and the language spoken elsewhere in the country is an invented form of Old Norwegian BUT each language has equal status. So if you go for, say a job in government, you have to show that you are fluent in whichever language is not your native one. TV is subtitled in either language. Icelanders can only understand Norwegian ( a tiny bit). No-one (from the rest of the Nordic group) understands Icelandic. Norwegians understand Danish and Swedish. Danes understand Norwegian but not Swedish. Swedes understand Norwegian but not Danish. Finns understand Swedish and some Norwegian but not Danish. No-one understands Finnish. So when looking for work within Scandinavia, the Icelanders go to Norway or Finland (where they speak English). The Finns only go to Sweden. The Danes only go to Norway. The Swedes only go to Norway if they must but mostly stay at home.
Update: a reader alerts me to, perhaps inevitably, the Swedish chef from the Muppets - who to Swedish ears sounds Norwegian.