If you're looking at your map. Locations tend to get a cloud over the tile they are in. Caves to the east is straight forward. There's a Glacial Fortress in the High Mountains you need a key to get in and I believe way in the bottom right there is something to find in the swamp. The swamp is kicking my teeth in, so I have yet to risk it.. Flooded Cave gave me half a key for Glacial, I assume the Swamp is hiding the other half. Also, I think Orson's house (Way North West) Gets a cloud sometimes.. I dunno, the map is rough, I need to take a close look at it.
Blah, it's night on my save. Either way, you might be able to see hints of stuff by looking closely at it. I only really know about the cave, the fortress and I've been murdered in the Deep Woods to the north.