The Fisherman by John Langan
Abe and Dan, coworkers, with nothing in common but their grief, find the bond of friendship and solace in the peaceful hobby of fishing the streams in upstate New York. Then Dan suggests Dutchman's Creek. Although Abe is unfamiliar with this waterway, he is more than willing to give it a go.
When one of the locals hears of their interest, he feels the need to tell them the legend of Dutchman's Creek, and why it is avoided.
Assuming it's no more than a colorful piece of folklore, a fish story as it were, they head for Dutchman's Creek......where they find a darkness deeper than any body of water, one that promises for a price.
Langan has written a fantastic novel, at turns achingly human, and gutwrenchingly horrifying. A grand tale of cosmic folklore that would have done Algernon Blackwood or Arthur Machen proud.
Highest possible recommendation.