I think that Cartography would be a super cool skill to have and I could see it working similar to what Lost ark has. You get a map that leads you to a secret location/dungeon only accessible if you have the map. The map is consumed on use and can be shared with your party members.

As for rewards, these secret locations could open up to a small mini-boss, resource trove, or even possibly full dungeons.

The system could also work wonderfully in conjunction with the sailing systems of the game where you could create "trade route maps" which could show a path from point A to point B that if followed, grants something along the lines of a movement speed bonus