I have skied many ski marathons: Lake Placid Loppet, California Gold Rush, Yellowstone Rendezvous, Rivière Rouge, Bretton Woods, Craftsbury, Blueberry Hill, Tughill, and several National championship 50k races. Also include a couple of larger event, as I have also skied the Canadian Ski Marathon many times, and quite some time ago I even skied the American Birkie. But the largest, the Norwegian Birkie, the Vasaloppet, the Marcialonga, and the Engadine are all still on the list.