It's episode 21 of Destiny. Finally, we learn which characters took the "Swim" skill and which figured it was just a waste of points! Bemused and annoyed Athrun is nearly best Athrun, but victim-in-a-sex-comedy Athrun barely beats him out! We get both in this episode, plus Zach hates something. Listen and find out what it is!
Dive on into it on Crunchyroll!