Race Details Event Date 05/12/26 Race start time(s) 5:30 PM Registration start 3:00 PM Event Location Cathleen Stone Island, Boston Harbor Event Address EDIC Dock Event City South Boston Event State MA Race ID 439 Race Description Cathleen Stone Island Outward Bound's Annual 4K Trail Run is the most unique and fun race in Boston! The 4K takes place on Cathleen Stone Island in the Boston Harbor, and in 2026 will be held on the afternoons of Wednesday, May 20th and Thursday, May 21st. This event offers companies a fantastic opportunity to enjoy a team-building activity with their employees, and individual runners to experience a trail run like no other, in one of the most beautiful spots in Boston. Your participation in the 4K Trail Run directly supports Cathleen Stone Island Outward Bound's core mission to provide free, hands-on science learning and social emotional development to Boston students. Event Information Registration URL https://runsignup.com/Race/MA/Boston/ThompsonIsland4kTrailRun Course Map Course map Website https://thompsonisland.org/support/fundraising-events/4k-trail-run/ Social Media Thompson Island Runners Instagram page USATF Cert. No. Uncertified Results Online Results Athlinks Older Results 2006, 2005, 2002GSRS Results Archive (Cathleen Stone Island)GSRS Results Archive (Thompson Island) Recent Results 2026202620252025202420242023202320222022202120212018201820172017201620162015 Race comments Race not held in 2020.