It's not easy to catch the reference at first, but when Odysseus talks about sailing into "the Kimmerian lands" (12) at the beginning of Canto I, he's alluding to the lands belonging to the Cimmerii, who were a mythical people living at the edge of the world. Remember that people long ago thought the world was flat and that there was an actual cliff or waterfall at the end of the world you could fall off. According to the poet Homer, the Cimmerii were a people who lived in constant darkness and mist, which Pound refers to by describing the Cimmerian cities as being "Covered with close-webbed mist, unpierced ever/ With glitter of sun-rays" (12-14). By having Odysseus travel to the darkest edge of the Earth, Pound sets the tone for his Cantos project as a whole, telling us readers that we're going to go on a journey that won't always take us to the nicest of places.
Lines 11-14: What's one of the worst parts about living at the edge of the world? We think it's interesting that it's not the noise of the thundering water, or the inherent danger of, you know, falling off the world. Nope, it's the total darkness. It's as if this place has never seen a sunbeam. Typically, light is symbolic of reason and insight. We wonder if this description isn't more piling on of the "at sea" depiction of humanity as lost, ignorant, and desperate (check out "Imagery: Sailing" for more). At the very least, it's in keeping with that idea.
Lines 15-16: Yeah, folks are pretty miserable here at the end of the world. It's pretty much what you might expect from a group living in year-round darkness. Bad times, gang.