The most unsettling thing about "The dying ocean" is how little of the dying it shows. The title announces the subject, but the six lines never use the word. The speaker says only that the sea "did not seem ill." The poem is built on the gap between how something looks and what is happening to it. Something can be failing while appearing perfectly well, and that appearance may be the most dangerous part.
The opening line sets the trap. "A most pleasant ark" sounds courteous and slightly old-fashioned, like a guest praising a comfortable room. An ark is a vessel that carries life through a flood, so calling the sea an ark is a striking reversal. The sea is usually the thing the ark floats on, but here it is the refuge itself, a container of living things. That makes the later word "ill" more jarring. If the sea shelters everything else, its sickness leaves nothing to shelter it. The poem never states this. It leaves the idea implied.
The construction is spare. The poem is one sentence, spread over six short lines of four or five syllables each, with no rhyme and no regular beat. The brevity suits the subject, because the poem has little to say and cannot say it loudly. Enjambment keeps the reader leaning forward. Line two ends on "which" and line four on "but," so each time the sense hangs in the air for a moment before the next line completes it. The single full stop comes only after "world," so the verdict is held back until the very end.
Sound does quiet work too. "Sea" and "seem" are close in sound, and the echo ties the sea to the idea of seeming, which is the poem's real worry. "There or here" chimes like a nursery phrase, almost a shrug. Its effect is more disturbing than its tone, though. The speaker has looked in more than one place and found nothing visibly wrong in either. The poem never says where "there" and "here" are, so the phrase works as a gesture toward the whole expanse of water. The wider the search, the more worrying the lack of evidence.
The last three lines hold the poem's central turn. Grammatically, the sea "did not seem ill, / ... but like a king." One appearance is swapped for another: the sea doesn't look sick, it looks regal. The king, moreover, "knew / nothing of the world." The choice of "that" rather than "who" makes him sound faintly like an object. The comparison suggests a ruler sheltered by his court, surrounded by comfortable surfaces, with nobody willing or able to tell him what is wrong. The image is also paradoxical. The sea covers most of the earth's surface, and the poem makes it ignorant of "the world," as though even something so vast could be cut off from what is happening to it.
The title makes it tempting to read the poem as being about damage done to the sea by people. That is an inference from the title, since the lines themselves name no cause. It is a reasonable one, though, and it adds a second layer. If the sea is the oblivious king, the people who admire it may be the courtiers, pleased by the view and reluctant to look underneath. The "most pleasant" opening then reads as the speaker's own complacency, soon corrected by what they realise they have been missing.
What makes the poem worth reading is that restraint. It gives no statistics, no catalogue of damage and no appeal to the reader. It offers a calm surface, a strange simile and a title that contradicts the mood. The alarm comes from the reader noticing that mismatch. A poem that shouted about illness would be easier to dismiss, but one that politely admires the patient and then lets the word "dying" sit in the title makes the reader do the worrying. By the final word, "world," the subject has widened from one body of water to everything that depends on it.