But these currents can pull swimmers into the ocean, moving at a speed of two metres per second.

Rips are strong, narrow currents that draw water directly away from the beach and can be deadly for swimmers and onlookers, suddenly pulled into a lifesaving situation.

ACM spoke to University of Adelaide lecturer Dr Masaki Shibata about the risks of swimming in rip currents and how to avoid emergencies in the water.

Before heading into the surf, Dr Shibata recommends finding a vantage point behind the beach and spending a few minutes watching the wave patterns.

Rip currents are typically found in still channels between breaking waves.

"If there's a calm area between the waves, avoid that," he said.

Avoid darker and deeper water, where seaweed and sand are sucked backwards in the ocean, not pushed forwards towards the beach, he said.

Rips will have sandy-coloured water behind the surf zone and fewer breaking waves.

Some rips change shape and location across the day, so check the break regularly.

Waves rarely move directly towards the beach, they tend to move to the right or left, Dr Shibata recommends taking note of the wave's direction and picking the right swimming spot accordingly.

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Before getting in the water, make a plan in case of emergency.

"If something happens, what are you going to do?" Dr Shibata said.

Think about mobile reception, access to floatation devices and where help is located, he said.

In Dr Shibata's experience as a surf lifesaver, swimmers stuck in rip currents tend to panic and don't alert fellow beachgoers they need help.

Parents, family members and onlookers, not planning to swim, can act instinctually react to drowning emergencies and jump into the surf to help.

Onlookers witnessing an emergency should think carefully about their ability, before launching to the rescue, Dr Shibata said.

Only strong swimmers, who can swim using long distance breathing techniques, should volunteer.

Strip off any unnecessary clothing and find a floatation device (a water bottle will work in a pinch), he said.

With waves pushing swimmers across the beach, a reference points can help with orientation, Dr Shibata said.

A colourful tent or umbrella on the beach act as a warning to swimmers who have gone outside of their safe swimming zone, he said.

Colourful swimming suits and caps help children and parents find each other more easily in the surf, and an eye-catching swimsuit can help surf lifesavers track swimmers caught in rips.

When caught in a rip, it is important to stay calm and focus on floating.

Rip currents move circularly. With patience, swimmers are often returned close to the shore or to a sandbank.

Swimming against a rip current will burn through any remaining energy and cause panic in the swimmer, Dr Shibata said.

Swim to the side of the current, parallel to the beach -- towards breaking waves.

While treading water, raise an arm in the air and signal for help from swimmers and sunbathers on the beach.