I'm well aware that the areas are known about, which is why I brought up the egg labelled "Underground". However, there seems to be a lack of documentation of the areas' locations and descriptions, and a hell of a lot of confusion on how to get that last egg. There is a comment on the egg page detailing how to get to it, but it is incorrect; River Road does not lead to Stone Heart; ANOTHER one of 710's maps, the Black Building, supposedly leads to it, but there might be a bug in the coding. The correct way to reach it is through Big Red.
I have made an elaborate flowchart of all of wataru's and n3's maps, along with every map that connects to them. You may view it on my talk page. The map is accurate as of v .103.