The speaker imagines themselves as a ship's captain who has finally unloaded a heavy cargo, and that cargo is pain. The unloading happens at noon, beside a wood the poem pictures as a "tract of masts," as if the trees were a harbor full of ships. It's a quiet, strange image: the forest becomes a port, and the speaker is docked there.
The last lines turn the scene slightly sour. The land is "like a merchant / without any receipt," a trader who takes the goods but gives no proof of the exchange. The poem suggests that the pain has been left behind, yet nothing confirms it is settled or gone. The land accepts it without acknowledgment.
The title, "Stranded," adds to this. The relief of setting pain down is mixed with being stuck, perhaps cut off from the sea and from movement. The mood is calm and watchful, a little lonely, with relief and uncertainty held together and no neat resolution.