Olson starts with something lovely, the sunsets, and then drags us straight down to the muck on the harbor floor. The poem is really one long sentence that slides from sky to sediment, as if the eye can't help following the view downward. Rubbish sits on the bottom and ferments, and gas bubbles rise and pop at the surface. The speaker tells us to watch them break and imagine the smell, then admits the smell is real: at low tide it's unbearable if you live beside the Harbor Cove or the Inner Harbor.
The speaker sounds matter-of-fact, almost like a neighbor who knows the place too well to romanticize it. There's no outrage, just plain observation. The mood is earthy and a little uncomfortable. The line breaks and the unpunctuated flow make the bubbles feel slow and steady, rising whether we like it or not. Beauty and decay are presented as part of the same place, and the poem refuses to pick only one.