The speaker is surrounded by people but feels completely alone. The poem's central comparison is to the sea: vast, empty, and cut off from everything else. Even in a crowded room, the speaker feels as isolated as someone standing at the edge of open water.
The details of the room add to this. The white walls feel blank and cold, and the noise somehow turns into quiet, as if the speaker can't connect with any of the voices. The "fake smiles" and "rigged talk" suggest conversations that feel staged and empty, with nobody being honest. That may be why the speaker has given up on joining in.
The short, simple lines and the repeated "still" give the poem a flat, tired mood. The final line, "Nowadays, alone I walk," hints that this feeling isn't new. The epigraph, "To the sea, I walk," suggests the speaker is drifting toward solitude, maybe even choosing it, as a relief from pretending.