When exploring dungeons, sewers, cavern layers, caves, etc. I am often frustrated by having to re-explore an area that I have already passed through in order to find my way out, due to that area becoming blacked out again as if I had never been there (perhaps due to transition from one area to another?). Sometimes I explore an area thinking it is a new branch of whatever I am exploring, only to realize that it is a part that I already finished exploring.
I do not think this is entirely bad. After all, it is unrealistic to expect your intrepid dungeoneer, spelunker, septic scourer, or urban explorer to keep a perfect map in their head of where they have been.
My solution: give adventurers a mapping skill that is affected by the spacial sense and memory attributes. Allow them to actively memorize an area as they explore, and prevent it from getting blacked out due to area transitions or whatever it is that makes that happen. The amount they are able to keep memorized or the length they can keep it memorized would be determined by the mapping skill. The memorized area would remain mapped until mapping mode is toggled off, fast travel is used, or their memory reaches its limit. Mapping mode could (perhaps) lower your speed a little, dependent on your skill level.
I think this would make exploration more fun without taking the challenge out of it, and increase its realism. It would make the adventurer's memory what counts in this aspect of the game, rather than the player's.