Seeing
"A Grave" is all about the act of seeing: words like "looking," "view," "look," recur frequently. The speaker is looking at someone else looking at the sea; the sea looks back at everyone. Moore plays with our understanding of looking vs. knowing, suggesting that the man blocking her view looks and thinks he knows, but that she has a more nuanced understanding of the sea because she knows that looking at it cannot begin to encompass its truth. She also suggests that one can look at small things—waves, birds, tortoise shells—to get a glimpse of the larger thing.
The Sea
The sea defies our understanding; it is opaque and mysterious, a place of death as well as life. Whereas some men think they grasp its essence, Moore knows better. She does not presume to think she can exercise power over it, preferring to contemplate its particulars and acknowledge its sublimity. The sea is depicted as indifferent to man, as a place where things "turn and twist" without "volition [or] / consciousness." It is beautiful, yes, but that beauty is "rapacious" and leads men to underestimate the sea's nature as "that ocean in which / dropped things are bound to sink."
Men
The one man that stands in front of Moore on the shore, thus blocking her view, can be viewed as representative of all men. After all, Moore later writes, "men lower nets, unconscious of the fact that they are / desecrating a grave." These men are depicted as blithely unaware of their insignificance in the face of nature, callous and arrogant, and privy to erroneous assumptions regarding their own power. This position contrasts implicitly with Moore's own as a passive viewer; but this passivity is the essence of her poetic vision, allowing her to be thoughtful and perspicacious about her relationship to the sea.
