Bill Sycalik posted the challenge of running a marathon on this small island:

 I am on a full-time life experience project to run a marathon in all 59 U.S. National Parks (www.runningtheparks.com). I just completed marathon #38 since June 2016 on Garden Key at Dry Tortugas National Park in Florida. Garden Key is the second largest island in the Dry Tortugas, about 14 acres in size, and has a 0.6 mile trail around the outside of Fort Jefferson on the key.