The speaker is awake, or half-awake, in the dead middle of the night, and nothing feels solid. The ship is "not the ship," the ending is "no end": the poem keeps taking away the things it names, so that even simple words slip out of reach. That is how a mind behaves at two a.m., when thoughts loosen and nothing seems to have a fixed shape.
The speaker calls their bed "lost," as if the place they sleep has drifted away from them. Judging by the ship, the image suggests a sense of being at sea, unmoored. Then comes the strangest line: dreaming of "clothes of cold water." Water can't be worn, and it has no edges to hold. It suggests a covering that offers no protection, only chill and exposure. The mood is lonely, eerie and dreamlike. The speaker doesn't seem panicked, just quietly displaced, floating in a night where nothing stays put and nothing quite ends.