The grey sea and the long black land; And the yellow half-moon large and low (1-2)
There are lots of adjectives in these two lines: grey, long, black, yellow, large, and low. These modifying words are all relative to the person viewing it. What the speaker thinks is "yellow" or "low" (or "long" or "grey") might not appear so to somebody else, a point that underscores the poem's interest in subjective points of view.
And the startled little waves that leap In fiery ringlets from their sleep (3-4)
The speaker here describes the waves as if they were both little animals (notice that they "leap […] from their sleep") and balls of flame ("fiery ringlets"). This strange hybrid figure points to the speaker's active imagination. He has the ability to reinvent the world according to his own taste.
Then a mile of warm sea-scented beach; Three fields to cross till a farm appears (7-8)
While a farm appearing seems normal enough, in a poem that is obsessed with perception it takes on an added importance. The fact the farm "appears," almost as if it were something supernatural, again emphasizes the poem's interest in the speaker's unique, individual perspective.