there’s a whole pond in the middle

Well yes, but actually no.

That part in the middle is land that has a miles-thick pile of ice on top of it. There's probably not any significant amount of liquid water on that land under the ice right now, and (in the long term) there probably still wouldn't be any liquid water on it because isostatic rebound would cause the land to lift if the ice were removed. I haven't found any sources that definitively claim whether the magnitude of the rebound would be enough to get all of it above sea level, but my guess is that it would.