What do you mean, "aquarium?" [with the same questioning lilt.] Have you never been to one before? I mean, neither have I, but that's only because I just haven't chosen to go to one, not because I don't have anyone to go with.

[... oh, he can probably invite hajime and the others actually... would they be interested..? well, he can't ask them now, but hm.]

It's a water zoo.