Ensolite Foam Pads
Many of us have slept on those blue (or other color) closed-cell foam pads. They are much warmer than air mattresses or open-cell foam self-inflating pads (such as the “Thermorest”) because the closed cells mean thousands of tiny, separate air pockets, the key to insulation. But they are handy for much more than sleeping on. Buy an extra one (they’re cheap) and cut it into pieces for sitting or kneeling just about anywhere. Fasten one to your canoe or boat seat, use them around camp, or take one out to your deer stand. Stick one in your day-pack when cross-country skiing, and when you all stop for a trail lunch you’ll have the warmest seat in the woods!
You can also buy them commercially as a sitting pad here.