Answer:
Unferth is “sick with envy” (l.502) of Beowulf’s reputation and courage. From a dramatic point of view, Unferth’s challenge gives Beowulf a chance to demonstrate his skill at boasting. Boasting was considered a legitimate way for a warrior to enhance his reputation, and as Beowulf tells the story of his swimming race we learn that the hero is as good at boasting as he is at fighting.
Step-by-step explanation: