Thumb Coast Ultra & Relay - 50 Mile, 50K, & 50 Mile Relay 2026

The 50-mile race begins on Lake Huron at Harbor Beach, sending runners across Michigan’s Thumb to Saginaw Bay in Caseville. The Thumb Coast Ultra & Relay is a spring ultrarunning event held in Caseville, Michigan, offering a 50 Mile, a 50K, and a 50 Mile Relay. The relay also starts in Harbor Beach, while the 50K begins and ends in Caseville. The course follows mostly dirt roads through the Thumb, featuring clearly marked turns, aid stations, and ample cutoff times. This event is suited for first-time ultra runners, seasoned athletes, relay teams, and those aiming for a quick finish. The 50K also has a ruck division included in its results. The unique challenge, reflected in the event's name, is that 50-mile finishers arriving in Caseville before sunset receive additional prizes for beating the sun.