Hundreds of sharks were spotted Wednesday off the coast of Singer Island.
Typically blacktip sharks appear in mid-January, but a warm winter may have delayed their migration down to Palm Beach County.
Shark expert Jim Abernethy believes sharks have less motivation to move south because of warmer waters.
"There's been many more in North and South Carolina and I believe it's because the temperature of the water is definitely warmer so they're much farther north," says Abernethy.
Blacktips usually get up to six feet and it's not uncommon for them to swim close to shore.
Ocean Rescue had the double red flags up Wednesday urging people not to swim.
Abernethy says people should not worry. "I would venture that all of these guests that are on the beach have been swimming with sharks without even knowing it."
Sonya Didas is staying clear of the water. "I'll go to my ankles, but I don't need to test the sharks' ability to bite."