Bunny boots... If you're in a cold environment don't listen to these guys recommending the sorels. Great boots, but as soon as you sweat and get that insulation wet your feet get cold, or at least that's my experience. The insulation in the bunny boots is confined inside 2 layers of rubber, so as long as you don't puncture that seal the insulation will never be compromise by moisture. Since the interior layer is a mostly rubber like compound if your feet do get wet, they act as a bit of a wet suit where your body temp stays sort of trapped inside the boot.
I've had many occasions of stepping in overflow and getting a soaker with them on. Your foot is cold for a few minutes, but just dump the water out and your foot will be comfortable again in a few minutes.
With that said, they're heavy, big and clunky and not great on ice, but as long as I can find them they're what I'll be wearing in the deep cold.