After searching for more than 18 hours, the U.S. Coast Guard ended its search for a missing swimmer Tuesday night.

Crews searched more than 450 square nautical miles for the individual who had been reported struggling offshore near Seagrove Place in South Walton.

The Walton County Sheriff's Office received calls from witnesses who said there appeared to be a man far offshore struggling to stay afloat, according to spokeswoman Corey Dobridnia. Deputies who responded by boat and personal watercraft said they thought they saw a man go underwater.

Officials said that ultimately there were no signs of a distressed swimmer and had no correlating reports of missing people.