we strolled the deck constantly , up and down , marking off miles as we conversed of everything and nothing , pointing out to each other the phenomena of a sea voyage ; the spectacular sunrises and sunsets , schools of strange green and silver fish , enormous islands of floating seaweed , harboring thousands of tiny crabs and jellyfish , the sleek dolphins that appeared for several days in a row , swimming parallel with the ship , leaping out of the water now and then , as though to get a look at the curious creatures above the water .