Many of the Red-throated Divers were flying in to feed from breeding sites in the mountains but I think that the majority of Black-throated were non- or failed breeders.
One morning I had a group of Black-throated Divers feeding very close to the shore and they were so confiding that I was able to get down to the waters edge and lie down to take pictures. It was overcast so the light wasn't the best but here are the best pictures I took with a variety of exposure settings.