Can anyone help me create a puzzle?

[dramaticat]

This seems like a good place to ask

I am part of a team creating a treasure hunt for my drama society. Our idea is that we get them to construct their own treasure map throughout the hunt, so that they end up with an island with a number of features on it, e.g. river, mountains, waterfall, cannibal village - you know the sort of thing. Then when they get back to base, they're given the final puzzle to locate the exact position of the treasure on the map. I've been tasked with making up this final puzzle.

What I'm looking for are clues along the lines of: 'The treasure is not west of the mountains' and 'The treasure is not north of a high place' and 'The treasure is either near the sea or the waterfall'. I need to construct a logic puzzle whereby these clues eventually lead to a particular square on the map. I've no idea how to go about it though. The number of feature on the map can be flexible, but probably a maximum of 7.

Is anyone able to give me any pointers, or are there any useful websites I can look at?

Thanking you in advance.

[Bunnylump]

Oh, come on, Scurra? Cenwulf? Surely this is right up your street?

[dramaticat]

After I expounded at length about the sort of clues we might use (without coming up with a puzzle myself), Ian said he had an idea how to approach it. There's no sign of the finished puzzle yet, so any other suggestions would still be welcomed!

As it happens, we've decided to postpone the treasure hunt until next spring for various reasons (including not enough people being around the first week in September to get a decent prize from the entry fees!), so there's no immediate rush, but we need to get this part of the hunt sorted before we can work on the other clues.

[Bunnylump]

I would offer to help, but my puzzle writing is a very haphazard process (I'm sure you will be astounded to hear ) which generally involves me coming up with some random plan in my sleep and then trying to make it work for a couple of weeks and failing.