I bought a pair of "arctic boots" that are amazingly comfortable and warm. My feet can stay warm in temperatures that would freeze the rest of me. I also have an extra pair of arctic boots from my cold weather infantry days in the Marine Corps that saw some drasstically cold temps and kept my feet warm. They aren't as comfortable as my new boots, but they are alright. I am sure you can find either kind online or at a surplus store. We always called them VB (vapor barrier) boots.