The idea of playing a game under the water is interesting enough, but the enthusiastic response tells him he's picked a good subject for Tidus (even with the slightly exasperated ending.)
"How fascinating. I assume there is magic involved in your propulsion? Are there set roles to play in the... Is the water in a particular shape?"
He was going to say 'field' and then realised that couldn't be the name for obvious reasons.

He intently reads through the pages about the sport Tidus is referring to.
"I have a few unread academic texts I wanted to finish, but if it is not that precise an order then I will refrain. Especially as it would be costly to order an article I would only read once."

He flips a couple of pages as he thinks about what he reads at home.
"I read many things, when I was younger I read mostly non-fiction but now I have broadened my scope. I like to read poetry to relax."