A beautiful bird, pity it has such a terrible name.
In the UK, we call them "Great Northern Divers" a name I've always felt was more deserving of the bird than the North American "Common Loon".
Having said that there has been a relatively recent "rationalisation" and "Internationalisation" of English bird names so maybe we should also now be using Common Loon in the UK, where they aren't that common.
I have just checked and it seems that Common Loon is indeed the official international English name. It also seems there had been an attempt at compromise by calling it the Great Northern Loon, but this has been abandoned in the most recent list.
http://www.worldbirdnames.org/bow/loons/Having said that, the most recent list for the UK by the British Ornithologist Union (sponsored by Leica btw), which says it is following the guidance linked to above, still has it listed a Great Northern Diver
http://onlinelibrary.wiley.com/doi/10.1111/ibi.12536/full.
So I'm lost now

They still make for great photograph, what ever they are called.
Graham