Discuss the Seafarer's ambivalence about where, and with whom, he belongs.

Because "The Seafarer" begins with an extended passage detailing the cruel life of the seafarer, a theme that becomes more pervasive in the middle and end of the poem, it is easy to overlook the seafarer's own admission that he is not just using the sea to get from one place to another but that he is drawn to the "atol ytha gewealc" ("the terrible tossing of the waves").

There were times when the swan's song/I responded to with pleasure,/the sound of the gannet/and the curlew's voice/in place of the laughter of men,/the singing of the gull/rather than the drinking of mead. (ll. 19b-23a)

Clearly, the pull of the sea, despite the sea's physical hardships and isolation, is too strong for the seafarer to resist. As he notes in these lines, the seafarer, at least some of the time, absolutely rejects life on land and its human fellowship in favor of the hardships, but joyous hardships ("voice of the curew," "singing gull"), and isolation of life amidst the waves.
Throughout the first half of the poem, the seafarer juxtaposes life on land, in which "cities grow fair, the fields are comely" (ll. 48b-49a), with life on the sea where "all these things compel/the man of spirit . . . to travel far/on the paths of the sea" (ll. 50a-52a). Life on the sea, then, despite its spiritual deprivations and physical stresses, attracts the seafarer precisely because such a life is devoid of mankind.
Later in the poem, the seafarer expresses his regrets that all things of man--power, riches, warrior glory--have passed away, a very conventional (from the Christian viewpoint) set of beliefs, and he looks forward to "the Lord's joys," another conventional theme in Old English poems that form a bridge between pagan and Christian belief systems. One cannot escape the impression, however, that the seafarer would rather be eternally at sea, battling the elements, enjoying the beauties of nature, but alone.