What is red tide?

What is the theme of Henry Wadsworth Longfellow's "The tide rises, the tide falls"?

• The tide rises, the tide falls, The twilight darkens, the curlew calls; Along the sea-sands damp and brown The traveler hastens toward the town, And the tide rises, the tide ...show more

• Answer:

  the theme is that people die but nature still goes on cyclically and without interruption despite the death (of the traveler)