DavidS wrote Except for the occasional time when we have a story that takes more than one book (the Kingdom novels, the Ravenette war) we generally don't know what we're going to write until we get together to plot the next book. So, no, we don't have plans to write an ice world book. Or a sea world, or a desert world, or a deep space battle, or anything else. We don't know what we're going to do after the one we're working on now.

If the plot takes place in a sea world then this would remind me of an old computer game: X-Com: Terror from the Deep.