O Swedish Island

Reading through "O" many times I get the feeling of progress. The first stanza is only two lines, the next is three lines, then three, then five, then four, then five. You can feel the constant movement is the first stanzas. This island is changing the neighborhood. As your moving along this island, around the corner you see a mighty galleon surrounded by flowers. Then around that you hear horns blasting and ships moving along the shores. It's a busy atmosphere yet the people seem complete and content with how things progress (living in the now).
The ending of the poem gives a sense of uncertainty. The ending words of the lines are sometimes, trembles, explanation, end, nothing is, future. You wonder if "we don't need much more to keep things going" is really going to keep us going. Do we need an explanation for the things we do? Should we worry about what we will end up with? Or are we more like this island where things come and go and you just move with the waves?