A mysterious island that doesn't show up on any map. Full of signs of human life, yet also lacking in any people living there. Wrecks of planes and boats alike litter the island. The terrain and life on the island sometimes seem unreal, with a strange cacophony of different plants and animals.
Many of the animals are strangely hostile. Even being almost entirely unprovoked they're willing to attack any human they come into contact with.
With the signs of human life, there are many things left behind, useful or not, as well as maybe more secrets if people are willing to search for them.