I think many people are scared by the strange appearance of a Swedish Nyckelharpa , but it's very close to being a Viola!  ...just tune your Viola D string down 1 whole step to C. 

It has extra sympathetic strings (not played) to sound more haunting than the Norwegian Hardanger Fiddle, is maybe easier to play chords - and the way it is held to be played looks MUCH more comfortable than the way we play a big Viola!  AND, if your instrument is tuned well, you don't have to worry about intonation 🤗 - because it uses keys!  ...the only downside is a little noise from using the keys, because they are mechanical, but still cool. 

A Brief History of The Nyckelharpa - from the American Nyckelharpa Association.

I think this is way cooler - I've attached a GREAT pdf "The Nyckelharpa in It's Historical Context" by Karen Myers.  She shows an in-depth historical overview of not only Nyckelharpa, but all the related instruments - fabulous photos! 

...check out the attachment.

Many Nyckelharpists also play the Fiddle! 

I've posted wonderful tune tutorials by Emelie Waldken in The Vals - how complicated can it be? Thread & Anyone Interested in a "Scandinavian Fiddle Genre"? Thread.  Sometimes she teaches tunes using the Nyckelharpa, instead of her Fiddle - never seems to be a problem.