No matter what environment you find yourself in, there is a potential shelter that can be implanted to provide you with a level of safety and survivability,

Just about every known culture of humankind has realized and used the shelter as protection from the elements of nature, predators, and other humans.

This means that as far back as cavemen, they understood the benefits of "being in a cave". Because the nature of your survival often depends on the environment that you find yourself in, each major natural biome has different needs, functionality, and building materials available to it.

A winter-based structure is going to be extremely different from that of a desert-based survival shelter, a so on from a woodland structure. Each of these environments has a greatly different range of potential dangers, risks, and hazards to deal with.

In a swamp, you are not entirely likely to suffer from sunburn or lack of water. Stuck on a raft in the middle of an ocean and the sun becomes your enemy and there is water everywhere that you cannot drink.