When I choose to review this skill, it tends to start with transcribing Hungarian. This is extremely frustrating since I've generally forgotten all the new words and concepts of the exercise when I begin it again. How about starting with the easiest exercises, namely translating written Hungarian to English? That way I could at least remind myself of the vocabulary with hover hints.
In the discussion belonging to another sentence, somebody explained that "el" with verbs of motion can also mean a certain completeness of the action (much like "meg"). I'm not a native speaker, but I assume this to be true for this sentence as well, as in "We are swimming (and we hope to reach) that island" as opposed to "we are swimming somewhere in the direction of that island" (without the "el"). www.hungarianreference.com also mentions that "el" (and "ki" as well) can have this meaning.
It would be very convenient if subtleties like this would be explained somewhere in the lesson notes, since it is already hard enough to get an intuition for these preverbs.