Well, I did ask for that earlier, just to see what people come up with.
See, if we can only make exploration interesting with combat, then it isn't an entire pillar of the game by itself. It needs to be able to stand alone. I'm not saying it is best when standing alone, or that I never want to see combat, but that if we looked solely at exploration challenges, with no combat or social elements, we could still make them engaging using the rules in the core game.
And so far... it seems that you can't do that, not without stripping away multiple PC abilities, focusing exclusively on low-level play, and forcing the players on a clock to prevent them from simply taking their time and succeeding anyways.
I mean, can you even challenge a high level party with exploration exclusively? Travel is meaningless to them, disease and food and water are all challenges that are trivial to solve by the time you reach levels 13 and higher. And yet, I can challenge them socially, I can challenge them in combat. I've done it. But exploration seems to not function in the way that allows me to highlight it.