MARATHON (CBSMiami) – If you’re planning on traveling to the Keys early Saturday morning you may run into a slight delay.

The Seven Mile Bridge that takes travelers overseas to the Florida Keys will be closed for several hours early Saturday morning for the annual Seven Mile Bridge Run.

The bridge is scheduled to close at 6:45 a.m. but the Monroe County Sheriff Department cautioned motorists who have early morning travel plans to leave with plenty of time and to ensure they are on the bridge by no later than 6:30 a.m. due to expected heavy event traffic.

The bridge, the longest of 42 bridges that help comprise the Florida Keys Overseas Highway, is scheduled to reopen at 9 a.m.

The Marathon Runners Club’s Seven Mile Bridge Run began as a dedication run in 1982, celebrating the opening of the “new” Seven Mile Bridge. It is the only known run that is completely surrounded by water from start to finish.

The marathon’s field of 1,500 runners was filled within six minutes after online registration opened at 6 a.m. February 23.

Paul Marmaro, a fitness instructor from Delray Beach, has won the race eight times and continues to hold the course record of 32 minutes and 59 seconds set in 1998 and is registered for the race.

So is Jason Bodnar, a North Carolina dentist who has won five times despite dealing with a phobia of crossing bridges.