It's a good thing that Madoka is in much too good of a mood because of the nice location they're at to really think about how awkward this whole 'teenage girls being eaten' talk is with a trauma involving that lurking at the back of her mind..

But she's blissfully unaware, which means she instead can use all her brain capacity to answer Romeo's question instead.

"Down? Um.. I'm not sure.." She doesn't look bummed out, at least! Just genuinely worried! "I can swim alright, but I've never tried diving before! I didn't get to swim much back home.. Is it hard?"