The poem opens with a startling reversal: what vanished wasn't a ship but the sea. The title, "Aral," points us toward the Aral Sea, and the poem seems to be about a body of water that has disappeared, though it never spells that out. Instead, it makes the loss feel strange and almost unthinkable, then compares the sea to "a great plain going out," like a tide that never returns.
The speaker's tone is quietly baffled. The line about "what mad sort of testimonies / the seamen give" suggests that the people who knew the water now sound unhinged when they describe what happened, simply because the truth is so odd. The final image is the bleakest: sailors "forced to work on a highway / that would only stop." Their familiar workplace has become a road with no end and no water.
The mood is eerie, stunned, and a little sorrowful. Nothing is shouted. The poem lets the absurdity of the loss speak for itself.