Horizon of Darkness

Nikta thought it was appropriate to subtly hint that her echolocation doesn't work underwater, and Henry could have figured it out himself, considering how advanced science is in his world, as he described.

-- Yeah, exactly, echolocation! You can do it like dolphins, right? No? Why not? Oh, well, we should have recruited dolphins.
Henry stood there for a moment, thinking about something.
-- Well, let's try levitating. And if that doesn't work, we can tie a stick to something and throw it to see what happens.