In line 80 of "The Seafarer," the speaker begins to talk about the present state of the world—what does he think of it? How do these thoughts contribute to the poem's elegiac tone?
The speaker mourns the loss of great leaders and rich empires. He laments the fact that the world is losing its "Golden Age" of heroes. It is the passage from a warrior-based society to a Christian society. Even though he ends the poem with an embrace of Christian spiritualism and Heaven as the divine, final destination, he does express a melancholy tone when he notes the transition from the heroic or Pagan age to the Christian era.
This duality is characteristic of other works that discuss Christian and pre-Christian philosophies and eras. Beowulf is a prime of example. In that work, the heroic age is celebrated, but one can see Christian ideas seeping into the text and therefore the culture of that time. In "The Seafarer," the speaker mourns the loss of that heroic age, and this does add to his sorrowful mood when describing the difficult life of a sailor. He is therefore exiled from that heroic age just as he is exiled from life on land. He feels these two losses in similar ways.
In the end, thinking more in spiritual terms, he is also exiled from Heaven, so his solution (in transitioning to Christian themes) is to seek a more spiritual life in order to get to Heaven. Then his sorrow is pushed aside so he can focus more on the Eternal.