State Road 686 (SR 686) is an east–west route in Pinellas County, running from U.S. Route 19 Alternate (Alt. US 19) in Largo east to an intersection with SR 687 (4th Street) and SR 694 (Gandy Boulevard) in St. Petersburg, Florida. Originally, SR 686 extended further west, ending at Gulf Boulevard in Belleair Beach, next to the shores of the Gulf of Mexico.