Hidden around the world as very subtle portals once you enter escape isn't easy. Sometimes you may have to deal with monsters (mcmobs), maybe a puzzle (redstone), or perhaps its just a simple rift with a very hard escape portal to find. No matter what the challenge is once you complete it you will rewarded with some type of prize. From pets, mounts, gold or even some special resource area. There is always something to find within a Rift areas.

If you accidentally enter a rift area you can do /spawn but you give up any rewards.