Laavu, a traditional Finnish shelter any passerby may use. Will build my own one day. We have used the American version in the Cascades while snowmobiling . They are usually found stocked with basic supplies for a few days survival if needed.
The wood fired hot tub is provided with a remote thermometer and an alarm that can be used to monitor the water temperature. If the water temperature is low, more fuel can be added. If the temperature is high, cold water can be added to the tub.