Two people walk along a beach, heads tilted up, while a train passes above and the sea lies below. The speaker loves the salty sound of the waves and the salty tears on the listener's face, so the sea and the crying seem to blend into one feeling. It's a quiet, bittersweet scene, with a seagull drifting through damp clouds.
The bridge is the poem's steady watcher. It keeps looking "from the past / to the future," as if it has seen this place through every stage of a relationship and will keep watching long after. The ending turns more personal. The bridge, or the memory it stands for, is "crossed like wrong words" on an old page of love letters. That image suggests regret, or a love that has been revised and scratched out. The mood is wistful and tender, a little sad, with the sense that the speaker is looking back at something that mattered and can't be rewritten.