If you ever need to build a fire to cook or heat with out in the open and you are trying to keep a low profile and remain hidden. The Dakota fire hole is a good way of doing it. While it most likely won’t be totally smokeless it will have a lot less smoke than a traditional camp fire. The Dakota fire hole is also a great way to have a fire when it is very windy because the actual fire is below ground level so it doesn’t get blown out and the embers don’t blow around. Freedom of the Hills has a great tutorial with a bunch of pictures and tells you how to build a Dakota fire hole. Never know when you may need this info.
Dakota fire hole