Two silhouetted people paddle a canoe on the ocean during sunset.
two people paddle their boat on the ocean
People would be silhouetted by the sunset and appear shadowed.  A boat is another name for a canoe.
A canoe is a type of boat.  People paddle a canoe during sunset on the ocean.
Two (silhouetted) people paddle their boat (canoe) on the ocean as part of the description during sunset.