Forests and Jungles
The feeling of isolation is made so much worse by the knowledge that a friend might be just around the corner.
The same could be said for my Post Apocalyptia example, but in that friendlies are signposted to all hell, so much so that they might as well be carrying around a big sign saying “bandit bait”.
Forests can contain anything that nature is capable of creating. The Forest is about the encounters of a place crash survivor with uncontacted native tribesmen of an unspecified region. This brings out the fear of a more primitive culture who have adapted to an environment better than you have.
No matter what you’ll be trying to make yourself secure but these enemies don’t need security. This applies to any enemy in the forest, be they man or beast. A tiger is happy with a den and a hunk of meat, but a man or woman from urban life will think they need so much more.
Nature truly holds the advantage in forests so bring your tent and mosquito net.