Oh My Goddess! Vol 32

Ever since a cosmic phone call led five literal young goddesses - Belldandy, Urd, Skuld, and, like occasional vowels, Peorth and Lind - to live in college student Keiichi's residence, his personal life has been turned upside-down, sideways, and sometimes even into strange dimensions! Reach the beach! With both Peorth and Gate (finally) sent home, Chihiro ends up leading the rest along on a tradition that dates back to the Motor Club - namely, a training retreat that's a thinly disguised excuse for a vacation. And even though Keiichi can barely swim, he's starting to hear the siren song of the sea... The problem is, it's a real song, sung by a real siren!

Source: Anime News Network Encyclopedia