Aside from being a huge hazard to bathers and swimmers, they can also cause significant beach erosion, particularly channelized rip currents, which can stay in the same place for days, weeks and even months.

Here’s another boundary rip, sometimes called a permanent or structural rip, that is flowing offshore against the rock platform. You can see the green gap pretty clearly. It’s narrow, only a few m’s wide and it hugs the rock platform and would take you around the corner out of sight.

This picture is a good example of how to spot a rip from a distance. I had the advantage of height, which is always important, and I’m looking for narrow, dark, green gaps that extend from the beach through the surf – white is nice, green is mean!

But every now and then, drones capture incredible footage of rip current circulation like this one, sent to me by Tony Gibbs (@tonedrone on Instagram).

The thin green line. I love this picture. Most of the pictures I post on the Rip of the Month are channel rips, which sit in deeper channels between shallow sand bars, and appear as darker, narrower gaps between areas of whitewater.

This picture is taken from Sumaro Head, the eastern most point on the island. Hopefully you can see the pronounced narrow, dark channel heading offshore about 100 m down the beach. That’s the rip.

This is the 12th anniversary of the Rip of the Month feature. That's 144 rip current pictures if you're counting, which must represent the largest single collection of rip current pictures in the world! I really hope it's helped some people learn a little bit more about how to spot rips.