The way she says it implies that she has not had much contact with humans. It's reasonable to expect that, given her physical form.

"Ah, those will be important if we are assigned a mission in amphibian environments." He replies with a nod. "Might you be, ah, residing near the lake? I often visit it after lessons, so we may meet each other quite often."

He has a habit of going sailing or swimming whenever he feels like it, too. Another quirk that comes from being a reincarnated self of a historical naval commander.