... Icelandic and Faroese) have varying degrees of mutual intelligibility but it's asymmetrical. For example, of the big three, Norwegians understand the other two the best, on average. Danes are better at understanding Norwegian than Swedish (owing to the 300 year union). Faroese speakers are really good at understanding the big three. Icelanders suck at understanding Norwegian and Swedish but are taught Danish in school so do ok with that on average.

There's even a degree of overlap with German and other similar languages (Scandinavian languages are considered to be under the umbrella of Germanic languages anyway). It's all very fascinating.