The Tartarus Backyard Ultra is a true test of endurance, resilience, and strategy. Following Laz Lake’s original backyard ultra format, this event runs on an hourly loop until only one runner remains. Every hour on the hour, you must complete a 4.1667-mile loop (or 2.2 miles for the ruck division). Miss the cutoff, and you’re out. There’s no finish line—just you versus the clock. This is one of the most exciting and mentally demanding ultra formats in the world, now set against the rugged beauty of Riverside State Park.