Water 101

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Water 101

Tristan Gooley, the Natural Navigator, picks out five things to look out for the next time you’re walking on the beach. Find out more at

Illustrations by Holly Donnelly 

Rip current

Formed when water on the beach is pulled through a narrow gap, causing the water to accelerate, like when you put your thumb over the end of a hose. They can flow at two metres per second, faster than any swimmer.

Glitter path

The line of reflections that form on the sides of waves: they get narrower when the sun is lower, and broader as the waves get steeper.

Swash and backwash

Swash is the foamy water that is pushed back up the beach by a breaking wave. The water that flows back down to the sea is known as backwash.

Pin holes

These tiny holes are caused by water sinking into the sand, which displaces air bubbles between the sand particles. The holes are formed as they bubble up.

Rill marks

These ridges form when water that has sunk into the sand gets pulled back to the sea, carving channels.


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