The Unknown, or UNKNOWN, is the given name for any area that does not belong to any existing biome.
While being in an Unknown biome has no bearing on the player themselves, when in an any area with no defined biome the World Map undergoes a small change: it receives a static-like filter with faint lines going across the outer edges, and a scratchy sound effect will play for the duration that the map is open.
If in a defined space intended to remain hidden from the player's map, such as on Moustache Island or The Vaults, it will remain classified as UNKNOWN, but the Beatrix icon will also be replaced with a question mark which defaults to a specific spot in the middle of The Dry Reef.
Defined Unknown spaces
These locations are in defined locations on the map, but are programmed to be obscured from the player's map by defaulting to The Dry Reef with a question mark icon. Many of these locations are unloaded when the player is moved away from it to keep it hidden when not in the cell.