While I enjoy the current quest system a lot I do lack the possibility to discover a thingwall by completing a quest.
This makes it so that you don't necessarily have to go looking for them specifically. It would for example allow you to find a passage over the deep ocean without the need of a knarr or snekkja.
It should be somewhat regional and for example only discover the nearest undiscovered thingwall.
Of course a proper balance should be maintained as to not discover too many thingwalls too fast.
A similar idea could be thought out for discovering localized resources, whirlpools and whatnot.
In my opinion this does not necessarily impact exploration all that much as quests do tend to send you to many places.
However it would allow you to discover close by regional resources which you might have missed because you were not close enough to them.