Three short lines, and a whole image: mangrove trees standing at the water's edge, somehow carrying "news from sunk ships." The poem never says what that news is, and that gap is where its power sits.
Mangroves grow where land and sea blur together, their roots tangled in tidal water. The poem treats them almost like gossips or messengers. Anything lost at sea, a wreck or its cargo, might eventually drift toward them, so they become a kind of archive of what the ocean has swallowed. The repeated "trees" in the first two lines feels like a pause, as if the speaker is looking, then realizing the trees are more than scenery.
The speaker's feeling is quiet wonder, tinged with melancholy. There's no explanation and no drama, just a sense of attentiveness. The mood is hushed and mysterious: the living, rooted trees are linked to things that have sunk and vanished, and the poem asks us to imagine what messages might be waiting there.