A Boston Tradition Since 1907


The oldest open water marathon swim in the U.S. and affectionately billed as the “Granddaddy of American Open Water Swims,” the 8-mile Boston Light Swim has been a local tradition since 1907.

Participants begin the race in the water at America’s first lighthouse, the Boston Light on Little Brewster Island in the outer Harbor. The course continues past George’s Island and Rainsford Island, then along Long Island (and past where the Long Island Bridge used to stand), and around Thompson’s Island. Swimmers come ashore at the historic L Street Bathhouse in South Boston, home of the world famous L Street Brownies and the L Street Ice Swimmers.

This swim is perfect for seasoned cold water ocean swimmers and those who are working up to longer cold water swims. Many swimmers in the past have used this 8-mile, non-wetsuit swim to prepare for an English Channel crossing.

Come join us for a fun, fast marathon race in unpredictable, challenging, and totally fun conditions.

All photography provided by Thomas Mikkelsen unless otherwise noted



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BLS logo art by Mark Howley