Drifting in a rip current about 300 metres offshore (and counting) at Muriwai beach, one of Auckland’s high-energy west coast beaches, I started to think of the common advice given to people on what to do when caught in a rip current. “Just swim to the side” came to mind. Yes, that was good advice, but possibly not so good given that the rip current was so wide I couldn’t actually see either side.

I suppose I could have taken a shot at it Olympic-swimmer style, but I reasoned that by the time I made it to the side, if I made it at all, I’d be halfway to Sydney, so what was the point? Another stellar piece of advice was, “Don’t worry, the rip current will eventually bring you back to the beach.” Would it? Really?

I wasn’t convinced. It seemed pretty doubtful to me, not being able to see the beach I had been standing on only minutes before. All I could see were walls of water. Finally, I reminded myself that I should heed the advice, “Relax and don’t panic”, and was amazed that this provided me with absolutely no comfort at all. All I really wanted to do was pee in my wetsuit. I wasn’t sure if this was a sign of the extreme relaxation I was feeling because of my understanding on how to behave properly in a rip current or because I was on the verge of panicking.

Fortunately for me, I was floating as part of an experiment to measure the speed and trajectory of really big rip currents. Not too far away was an inflatable rescue boat with some very capable lifeguards aboard. By the time they pulled me out, I had travelled almost 300 metres along the beach in a channel feeding the rip current, which then took me almost 400 metres offshore at speeds approaching those of swimming world records. It was quite a ride, but if the boat hadn’t been there, I would have been in big trouble. Rip currents are responsible for hundreds of drownings and tens of thousands of lifeguard rescues on beaches around the world every year. Folks, a lot of our beaches have a rip current problem.

So what are these mysterious rip currents and why do they move so much water (and people) away from our beaches? Rip currents, or rips, are currents and just like river currents, they move water from one place to another, usually in one direction. So think of rips as rivers of the sea. Currents. Hmmm. Now there’s a term that tends to make the average person’s eyes glaze over. It shouldn’t though because water moves all over the place on many beaches and understanding how currents work and how to spot them may just save your life.

Whether you are aware of it or not, if you’ve ever swum at a beach with breaking waves, you’ve experienced some sort of current in action. It’s important to remember that currents don’t just move water and swimmers around, they also move sand and play a huge role in determining what your beach will look like on a day-to-day basis.

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In 1902, William Gocher, a newspaper editor probably trying to drum up some news, defied the ban on daytime swimming and went for a dip at Sydney’s Manly beach and was immediately arrested. Although the motivation for his actions remains unknown, it is often documented that this “hero of the surf” opened the floodgates for Sydneysiders to start swimming en masse during the daytime, whereupon many drowned – mostly in rips. In response, the iconic Australian surf lifesaving movement was born and the first surf lifesaving club was established in 1907 at Sydney’s Bondi beach – or Bronte beach, depending on who you talk to. It’s a touchy subject. Since then, lifeguards and lifesavers around the world have made an awful lot of rescues and probably saved tens of thousands of lives from the perils of rip currents.

It could be argued that, being a poor swimmer, perhaps it would have been better if, instead of being dragged off by the police, Gocher had been dragged off by the notorious “Manly Escalator” rip, thus becoming the first high-profile rip current victim in Australia. Maybe then, from the word go, rip currents would have been recognised as the biggest hazard on our beaches and would have generated the interest and attention among the public and media that they deserve.

Shark attack? Front page news. Rip drowning? Barely rates a mention. There often seems to be a dangerous degree of complacency and acceptance about rips. In 1967, Harold Holt, the then Australian prime minister, went for a swim just before Christmas at Cheviot beach near Portsea, in Victoria, only to drown in a rip. Nevertheless, some people still believe the conspiracy theory that he really secretly rendezvoused with a Chinese submarine. Rips just don’t get any respect.

They are also called a lot of different names, most of which are incorrect or misleading. This creates a lot of confusion. The term “rip current” was coined by oceanographers working in La Jolla, California, in the 1920s. The origins of why rip was chosen remain unclear, but it’s probably because most rips look like a tear, or gap, through the surf. If you want a nice, simple definition of what a rip is, here goes: rips are strong, narrow “rivers of the sea” that flow from close to the shoreline offshore to the extent of breaking waves, and sometimes beyond, at speeds sometimes faster than the average person can swim.

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So just how far will rip currents take you away from the beach? Well as exciting as it sounds, they won’t take you across the ocean from the east coast of Australia to New Zealand. It really depends on how big the waves are on the day. Rips will usually flow at least to the line of breaking waves and sometimes a little further offshore, so the bigger the waves, the wider the surf zone and the further offshore you’ll go.

Under normal wave conditions, typical channelised rip currents along the south-east coast of Australia will take you about 50 to 100 metres offshore. That doesn’t sound too bad, but it all depends on how far you can swim in the ocean, which is a lot different than swimming in a pool! Boundary rips are a bit different and because they tend to be forced offshore, they can take you further offshore than channelised rips, even under the same wave conditions. Flash rips generally don’t flow far, but because they often form off sandbars, you can still end up quite a way from the beach and in deeper water. However, some beaches always have massive surf and the rips are equally big.

The rip that I floated out in at Muriwai beach in New Zealand took me almost half a kilometre offshore and I was still going when the lifeguards pulled me out. If they hadn’t been there, I was looking at an awfully long swim … but more likely a helicopter rescue.

This is an edited extract from Dr Rip’s Essential Beach Book: Everything you need to know about surf, sand and rips, by Rob Brander, published by UNSW Press