Muck Boots

Check out the Woody Max from the Muck Boot Company. I've got a pair of the original Woody's, the difference being the sole on mine is not quite as aggressive. These boots are insulated but the are made of a breathable material.

Not sure exactly how it works, but your feet don't sweat any more than they would with a typical pair of hunting boots but they also keep your feet warm in the winter.

Very comfortable and well worth the $$ in my opinion.