The Indians boiled water in woven baskets. This was done by heating rocks and then dropping them into the basket. Be sure to observe the old warning against rocks from streams or wet locations. They can explode when heated. If you have the time, you could locate a clay source and make pottery. Steatite was used as an early non stick frying pan. The stone expands and conducts heat quite nicely. A hole may be excavated ( dug?) and lined with large leafs or plastic sheeting to make it watertight. Just know your plants and don't use any toxic materials.<br><br>