In the poem "The Seafarer," what contrast is established by the "yet" in line 58?
In the preceding part of the poem, the speaker is referring constantly to the suffering that seafarers undergo. He speaks of "fear" and of wondering what "Fate has willed and will do." He admits that the sea has "no rewards, No passion for women, no worldly pleasures." He even goes so far as to speak of the journey upon the sea as "exile."
Then comes the stark contrast with the words you mention. Let's look at the complete excerpt:
And yet my heart wanders away, / My soul roams with the sea, the whales' Home, wandering to the widest corners / Of the world, returning ravenous with desire, / Flying solitary, screaming, exciting me / To the open ocean, breaking oaths / On the curve of a wave. (58-65)
In other words, despite all of the negative things that the speaker has previously related, he cannot deny his desire to return to the sea. In the most important and meaningful line here, the seafarer admits that the sea is where his "soul" can be found. This turns the experience into a profoundly spiritual one. Further, the sea is his home, just as it is the "whales' home." It provides adventure, making him feel the draw of regular life more as he returns. Intensely exciting, the sea is where the seafarer belongs.