Final answer:
The novel 'Down to a Sunless Sea' is not directly referenced so the publication date cannot be provided without additional information. The poem by David Graham of the same title was published in 1978.
Step-by-step explanation:
The novel Down to a Sunless Sea is actually not referenced among the excerpts given, therefore,
you might be referring to the poem with the same title by David Graham or perhaps another work incorrectly attributed.
If you're referring to the poem by Graham, that was published in 1978.
However, if you are looking for information on a novel with this title, it would be helpful to provide the author's name for more accurate publication details.
The excerpts showcased do not provide a publication date but are indicative of detailed scene-setting, rich in imagery and allegory.
These passages include references to the misty conditions at sea, the transition of light to darkness, and the profound experiences of characters in these settings.