the seafarer

I don't think it is stated why he is on land, perhaps he is too old to be at sea. He does not like being in exile from the sea. The Seafarer proclaims that the Lord's joy is more exciting than a fleeting "dead life" on Earth. The wealth of the Earth will wither someday, because it cannot survive forever. Men and women on earth will perish due to either illness, old age, or armed conflict, none of which are predictable.