One boater was burned and at least one firefighter had to be treated for heat exhaustion as crews battled the blaze for hours in temperatures that hovered above 90 degrees.
The blaze is believed to have started when a generator on one boat backfired and then caused the boat to catch fire.
Between 200 and 250 firefighters battled the blaze for more than two hours before bringing it under control, said Billy McAdams, the chief of Townville fire station.
"This, as far as I can remember, is the biggest loss of boats we have seen," he said.
The number of damaged boats could climb in the coming days.
Greg Shore, an owner of Medshore Ambulance Service, said his personal boat was destroyed in the fire. He initially said Monday that the damage tally was believed to be around 30 vessels. Shore added late in the day that he believed many boats are still being evaluated for issues that, while not severe, are still damages.
Shore confirmed that the fire started on Dock 6 at the marina. Shore said it was a friend of his who suffered minor burn injuries.
"I talked to him, and he is going to be OK," Shore said. "He told me his generator backfired and caught his boat on fire, and his boat was in the middle of other boats and the fire just went from there."
Shore said the man was taken to the Joseph M. Still Burn Center in Augusta, Georgia, by helicopter and is believed to be in stable condition. His identity was not disclosed.
Lt. David Baker of Anderson County's Emergency Management Division said Monday afternoon that the the fire was being fought "by land and air." While initial reports indicated that the fire affected several docks, McAdams said later in the day that the damage was focused at Dock 6, which had room for about 45 boats.
The fire was reported just after noon.
Multiple medical helicopters were put on standby to respond to the scene and divers were also called to be ready to look for any people in the water.
Fighting the fire was further complicated by the amount fuel stored on each of the docked boats. Shore said his own boat had 200 gallons of fuel on it.
"You take 200 and multiply it by 20 boats, and that's what you have fueling this thing," he said. "We are just praying that the firefighters stay safe and hydrated."
Marina Road, which leads to the scene, was blocked to traffic and cars were rerouted toward Interstate 85.
Adam Medicus, 20, of Anderson, said his family was loading its boat onto a trailer when they saw the fire from a boat ramp.
“It was growing immensely, the amount of smoke," he said.
Medicus said he heard explosions — several “loud booms and bangs” — then saw things falling into the water.
“That is the biggest fire that I have ever seen in my life," he said.
The marina draws thousands of visitors from South Carolina, Georgia and beyond each year. It is also the site of an annual holiday flotilla that draws crowds from across the Upstate.
Emergency crews sent out a call asking for any available firefighters in Anderson County and Oconee County to respond to the fire.
Responding agencies included the American Red Cross and dozens of Upstate fire and emergency officials. Firefighters came from Center Rock, Townville, Zion, West Pelzer, Homeland Park, Ebenezer and Friendship fire stations, among others in Anderson County. Oconee County sent a fire boat and firefighters from Fair Play and other stations. McAdams said at least 24 fire stations responded to the marina.
The investigation is being handled by the South Carolina Department of Natural Resources. The agency investigates incidents that occur on state waters.
Fire ranks fifth among all causes of boat losses, according to Boat Owners Association of The United States, one of the nation’s leading insurers of boats.
The association suggests that boat owners get regular insurance checkups with their insurance carriers to make sure they will be covered in the event of a fire like the one at the marina. Some insurance policies offer full replacement, while others will partially reimburse repairs.