The Great Bay 5K is excited to hold its 27th annual race in 2025! The GB5K is the final race in the popular Seacoast Road Race Series and supports the non-profit Great Bay Stewards. The course passes the shores of Great Bay, and is a fun, fast, scenic, and mostly downhill event. In 2025, we are pleased to bring back the Great Bay 55K Challenge - run the entire 55 kilometers in one day, or complete the total distance anytime between October 1 - 25.