Rip currents have turned deadly this summer. Here's how to spot them and what to do if you're caught in one.

The greatest danger lurking in the waves at the beach this summer isn't a shark — it's a rip current. 

About 100 people drown from rip currents along U.S. beaches each year, according to the United States Lifesaving Association. And more than 80% of beach rescues annually involve rip currents.

Rip currents have already turned deadly this summer. Six people drowned in rip currents over a recent two-day period in Florida, including a couple vacationing on Hutchinson Island from Pennsylvania with their six children, and three young men on a Panhandle holiday from Alabama, officials say.