One of the things I love and appreciate about Ur (especially the bogs) are the vistas that are thematically consistent across a region, with landmarks visible in the distance that reveal themselves in different ways depending on how you move around in the landscape.
It should be possible using existing technology and might be cool to have a misc. island that is sort of a maze. You could enter the island and find the map disabled. Instead, you have to find your way through the landscape by paying close attention to the surroundings and the vista. Are you going uphill? Can you see this hill from somewhere else? Is there an island in the distance? Can you see it from somewhere else? Where does that put 'somewhere else' in relation to where you were?
Perhaps the payoff could be entry to another island that doesn't appear on the global map, with rewards of it's own. Teleporting could be disabled to both islands so you *have* to go through the first unmapped island to get to the second. Neither map appears on the global map. I'm just brainstorming here.