Rip Currents: fast, unpredictable and deadly | Photo: California State University, Long Beach

Rip currents are responsible for hundreds of drownings and more than 100,000 lifeguard rescues on world beaches every year. Learn how to avoid and survive these mysterious ocean rips.

Water moves all over the place, so rips are strong currents just like river currents. All beaches have their own particular currents. They're dangerous and deadly to swimmers, but also to all wave riders.

In unpatrolled beaches, surfers tend to trust their personal knowledge and their floatation crafts, i.e., their surfboards. However, rip currents will move anything and anyone.

If maritime conditions suddenly change, new channels of water will flow, pushing you to new areas. If you're tired after two hours of waves, a rip will certainly defeat you for good.

"The rip will not pull you under the water and your body has a natural ability to float. Being in a rip usually doesn't feel like anything because you are just going with the flow", writes Rob Brander in his book "Dr Rip's Essential Beach Book".

One of the most important rules is to never swim against the rip. Small rips will flow faster than the average person can swim. You'll get tired and start panicking.

If you get caught in a rip current, you've got four rational alternatives. First, stay afloat and signal for help. Then if possible, swim towards the side of the rip, having in mind that rips are quite narrow.

If you still can't get out of the rip, look for whitewater and breaking waves.

"Whitewater is good because it means the water is shallower, and you may be able to stand up. Whitewater will also bring you back to shore. When it comes to most rips, 'white is nice, green is mean'", adds the rip current specialist Rob Brander.

Finally, if you just can't get out, let the rip take you out the back until it stops. Then you'll be able to swim back to the beach through alternative paths.

There are fixed rips, flash rips, permanent rips, megarips and swash rips.

Fixed rips are the most common ocean rips. It sits in deep channels snuggled between shallow sand bars. They can stay in the sam place for days, weeks and even months. Fixed rips appear as dark gaps of calmer water between breaking waves and whitewater.

Flash rips move around all over the place, popping up and disappearing, and usually last for a few minutes. They are dangerous and form in larger surf. Flash rips flow quickly and are impossible to predict.

Permanent rips are influenced by topography, so they sit and reappear in the same spot all the time. They tend to flow further offshore than fixed rips. Look for dark channeling gaps.

Megarips are big, fast and rare. They only appear with storms and large swell. Swash rips are the combination of the uprush of water from a broken wave up the beach and its subsequent backwash down the beach. They may carry people into deep water beyond the shore break.

Get and discover "Dr Rip's Essential Beach Book" by Rob Brander. Find out what it means to be caught by a rip current.