Didn't I hear something about there being ten treasures in each level? I've played through the demo several times and I can only find nine. These are the ones I've found; maybe somebody knows of one I'm missing:

1. In the tunnel to the left after you've climbed up the first ladder.

2. In the room right after the boulder trap (w/ the scorpion/s that go/es after you when you pick it up).

3. In the room right after you press the button to launch the funeral barge.

4. At the bottom of the pool near where the funeral barge used to be.

5. In the cave before the first jeep-jump.

6. Near the commies (is that P.C.?) before the second jeep-jump.

7. In the cave before the last jeep-jump.

8. Near the Russians before the last jeep-jump.

9. The idol in the last cave with the spiral ramp.

10. ?

This is just a guess, but in the full game it could be past the gate the sharks swam out of.

The tenth treasure is where the boulder falls from.

Ah, you beat me to it. I just figured it out on my own and was going to post it here. Well, thanks a lot anyway, Drew (and Hamster, for that matter).