Don't feed the trolls guys..
Anyway, whether the interior is unknown or not. Like Sliver said, this is not about the interior; it's about the surface.
If someone provides a map, it gives the viewer the impression that that person knows what is located on that surface. When that viewer then proceeds to ask the provider questions about the map and it turns out that an essential part of the map (the outer ring, which determines its shape) is unknown, it undermines the credibility of the map.
That does not mean the map is incorrect; it simply is fair to ask questions about it and it's fair to be surprised when there are great unknown areas on it. Speculating that someone else's map is incorrect because there are might be unknown areas outside of the portrayed surface of the map is rubbish. The RE map is not showing the inside, and even if it did it is no valid argument to defend hiates in the FE map.
So.. it is unknown what is on the outer ring of this FE map.
Therefor nobody knows what happens if you would succeed in following the red line because and apparently nobody did.
Also, it is unknown what holds the water in.
Let's get on with your next question, Sliver. I'm curious to see if anyone knows the answer to that one..