In this poem, the speaker (Seafarer) discusses how harsh his life at sea has been. He makes particular notes about the cold weather especially in comparison with the cold, isolated feeling of loneliness at sea. He compares his rough life at sea with the more comfortable life on land. The warmth of shelter is more comforting on land and the life there is more social, less lonely than the life of a seafarer.
Beginning on line 11, the Seafarer notes how the waves leave him continually drenched. This makes the cold air even more unbearable:
pierc'd with cold
were my feet,
bound with frost,
with cold bonds. (16-19)
The Seafarer continues with more references to the cold weather in subsequent lines. But first he notes that men who live comfortably on land do not have any idea how miserable and sad his life as a seafarer has been. His descriptions of his loneliness are usually coupled with images of coldness. His line of being miserable and sad is followed by "on the ice-cold sea / a winter pass'd, / with exile traces; / of dear kindred bereft, / hung o'er with icicles." These are lines 28-31 of the first part/stanza and line 1 of Part 2.
Different translations of the poem show it divided in different ways. Some have it in two or three parts with no separation of stanzas. Some have it as one continual poem. And some divide the poem into stanzas of four to five lines. So, it's not clear what the first "stanza" is, but many of the translations have a first "section" and this seems to be between 15-30 of the first lines.