Edit: I forgot to mention, this door was already open when I first found it on my testing server.

This tunnel near the town of Nasdara has a blocked off room with a scarecrow inside of it. Upon further inspection, this room has an openable green door inside of it, and a server restart may let this door be open, allowing a player to see under the map very clearly.

Coordinates, as taken from VPPAdminTools: 9556, 156, 4369

Photos:

Simply go inside of this tunnel, and you will see this fenced off/blocked off room with the scarecrow. While a player cannot open this door without the use of cheats or admin tools, the server may open this door upon a restart/fresh load.

This door should be replaced with a non-openable door.