The waterfront areas of Long Island’s Great South Bay and the Fire Island National Seashore are the setting each October for the Northwell Health Great South Bay Run Half Marathon (formerly Entenmann’s before 2016), which also includes a 10K and 5K races that are both open to runners and walkers.
Great South Bay Run Half Marathon 10k & 5k
September 27, 2025
Bay Shore
Road
Ready to sign up?
100-500
Fast & Flat
Oceanfront
High: 73°
/ Low: 54°
Starting from the Bay Shore Marina near Islip, a town on the southern shore of Long Island, the race takes participants through much of this beach town’s quaint, cozy downtown streets, including Main Street and past Walker Park and Gardiners County Park.
Along the course, which is largely fast and flat and run entirely along paved city streets, runners also are treated to views of the architectural beauty of homes along the Penataquit peninsula as well as nearby Brightwater’s scenic Cascade Lake and the Brighwaters Canal area.
The out-and-back race takes a zig-zag route through town, alternately taking runners close to the water and then back toward Main Street, and finishes back at the starting line at the Bay Shore Marina.
Participants are limited to three hours on the course, which must re-open after that time due to traffic restrictions. The races begin at 7:30 AM with the half marathon, followed by the 10K at 7:45 AM and the 5K at 8:00 AM. The 5K and 10K races are open to both runners and walkers, while the half marathon is for runners only.
Overview
The waterfront areas of Long Island’s Great South Bay and the Fire Island National Seashore are the setting each October for the Northwell Health Great South Bay Run Half Marathon (formerly Entenmann’s before 2016), which also includes a 10K and 5K races that are both open to runners and walkers.
Course Description
Starting from the Bay Shore Marina near Islip, a town on the southern shore of Long Island, the race takes participants through much of this beach town’s quaint, cozy downtown streets, including Main Street and past Walker Park and Gardiners County Park.
Along the course, which is largely fast and flat and run entirely along paved city streets, runners also are treated to views of the architectural beauty of homes along the Penataquit peninsula as well as nearby Brightwater’s scenic Cascade Lake and the Brighwaters Canal area.
The out-and-back race takes a zig-zag route through town, alternately taking runners close to the water and then back toward Main Street, and finishes back at the starting line at the Bay Shore Marina.
Participants are limited to three hours on the course, which must re-open after that time due to traffic restrictions. The races begin at 7:30 AM with the half marathon, followed by the 10K at 7:45 AM and the 5K at 8:00 AM. The 5K and 10K races are open to both runners and walkers, while the half marathon is for runners only.
