Never Quit has brought thousands of people to Jacksonville Beach each year since the physical challenge started in June 2009.
But now complaints from police and the fire department have raised safety concerns.
Jacksonville Beach Police Cmdr. Gene Paul Smith told the Beaches Leader the event is not family friendly, but an extreme sporting event with the "possibility of mass casualties." Smith also recommended the city not have it back next year.
Never Quit includes a 5K run, a Trident Challenge, which is a variation on the triathlon, surfing lessons and a one-mile fun run.
"As events get bigger and grow, you are constantly striving to find new ways to make sure everything improves over the last year," said Erik Petroni, of Never Quit.
The Jacksonville Beach Police Department said the event is not off the table for next year, it just needs to work on a better action plan to ensure public safety.
Smith has not responded to News4Jax for comment.
Jacksonville Beach Mayor Charlie Latham said the problems of this year's event are an easy fix.
"We've got some lessons learned," he said. "I mean, it's a big event that grows a little each year, and we're ready to put a plan in motion to make sure we cover all the weaknesses that might have occurred this year."
Latham said the event and the city need better coordination and communication.
"Never Quit is a really good event for Jacksonville Beach," he said. "It's very family friendly. We get visitors from all over the country, and we are comfortable with the fact we can improve each year."
In 2013, a man had a medical emergency during the Trident Challenge -- a 500-meter ocean swim, a crawl through the sand, pull-ups and paddle boarding. He later died at a hospital.
That is the only recorded death since the event began.