The flow of ocean water along the coastline and beaches contains the normal push and pull with the tide.  When a strong storm or tropical cyclone turns up the waves off of the coast, it can increase the pull of water out to sea.  Rip currents are channeled or funneled currents of water away from the shore and can go through the breaking waves.  It is nearly impossible for strong swimmers to overcome the movement of the water.  When swimmers get caught, they can tire quickly, and often lead to drowning.  According to the United States Lifesavers Association, the average number of deaths is over 100 per year.  It is also responsible for over 80% of rescues performed by beach lifeguards.
 
To see examples of what rip currents look like, see the slide show below.

Rip Current Safety Tips- From the Nation Weather Service
 

When at the beach:

• Whenever possible, swim at a lifeguard-protected beach.
• Never swim alone.
• Learn how to swim in the surf.  It's not the same as swimming in a pool or lake.
• Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don’t go out.
• Obey all instructions and orders from lifeguards. Lifeguards are trained to identify potential hazards. Ask a lifeguard about the conditions before entering the water. This is part of their job.
• Stay at least 100 feet away from piers and jetties. Permanent rip currents often exist along side these structures.
• Consider using polarized sunglasses when at the beach. They will help you to spot signatures of rip currents by cutting down glare and reflected sunlight off the ocean’s surface.
• Pay especially close attention to children and elderly when at the beach. Even in shallow water, wave action can cause loss of footing.

If caught in a rip current:

• Remain calm to conserve energy and think clearly.
• Never fight against the current.
• Think of it like a treadmill that cannot be turned off, which you need to step to the side of.
• Swim out of the current in a direction following the shoreline. When out of the current, swim at an angle--away from the current--towards shore.
• If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore.
• If you are still unable to reach shore, draw attention to yourself by waving your arm and yelling for help.

If you see someone in trouble, don't become a victim too:

• Get help from a lifeguard.
• If a lifeguard is not available, have someone call 9-1-1.
• Throw the rip current victim something that floats--a lifejacket, a cooler, an inflatable ball.
• Yell instructions on how to escape.
• Remember, many people drown while trying to save someone else from a rip current.