A speaker sits alone in the dark by a turtle pond, unable to switch off his thoughts. He admits he is up late "for no purpose at all," yet his mind keeps circling through worries about the past, the future, and the present. The refrain "the turtles are asleep" returns again and again, and it works like a contrast: the animals are at rest, while he is not.
He tries to escape. He leaves the noise of talk and drinking, then wanders into a street full of music and bustle, but nothing comforts him. Back at the pond, he starts questioning himself. Is he a fool? Is he being used? Is he misunderstood? Then he asks whether he even has the right to ask.
The ending is quietly deflating. Maybe none of it matters, and he's just "some guy" slouching by the water. The mood is lonely and restless, but gently self-mocking too, as if he half-laughs at his own overthinking.