Dangerous rip current conditions continue along the North Carolina coast.
Red flags are flying at many beaches, warning prospective swimmers that it is not safe to get into the water.
"It's important for folks to remember that, on a day with the red flags out, there's the presence of rip currents," UNC Graduate Researcher Joshua Himmelstein said in an interview with ABC affiliate WCTI. "They may not be visible all the time, where you may not know where they are going to occur."
Rip currents are relatively strong narrow currents flowing outward from the beach, through the surf zone.
They kill dozens of swimmers every year by quickly pulling them away from the shore, tiring them out and ultimately causing them to drown.
In Oak Island this year, at least three people have drowned since June--all of their deaths are being blamed on rip currents. According to the National Oceanic and Atmospheric Administration, rip currents account for more than 80 percent of rescues performed by beach lifeguards.
"If you see a bunch of waves breaking and then an area where there are no waves, that might be a good first indicator that there's a rip current pulling water offshore or away from the beach," Himmelstein said.
What should you do if you're caught in a rip current
First of all, it cannot be stressed enough that you should not swim if the rip current risk is high.
Still, strong rip currents can happen on days when they're not expected. So if you get caught in a rip current, is there anything you can do to survive?
Don't fight the current -- fighting against the current will just tire you out quicker; you cannot outswim a strong rip current.
Swim parallel to the shore -- instead of swimming against the current toward the shore, swim sideways and try to escape the current.
"The last thing you want to do is try to swim directly in where it pulled you out, because it moves faster than an Olympic swimmer. So, unless your last name is Phelps, you're not going to want to try that," Himmelstein said.