A flood has covered the fields, turning familiar ground into what the speaker calls a "rank maze," a place that feels tangled, murky, and a little unpleasant. Into this scene, the speaker and a companion (the "we" suggests more than one person) go looking for a catch. They wait with "great patience," and the poem presents the result as "costly," which hints that the effort, or perhaps the situation itself, took something out of them.
The twist comes in the last line: "ling and wonder." Ling is a kind of fish, but pairing it with "wonder" turns the catch into something larger than food. The speaker seems to have found awe in the middle of a disaster. The mood is quiet and watchful, with a slow, patient pace that mirrors the waiting. There is unease in the word "rank," but the ending lifts it, suggesting that attention and stillness can reveal something surprising, even in a ruined landscape.