Pin Holes on the Beach

When a wave breaks it pushes foamy water up the beach, this is the ‘swash‘.

Some of this water flows back down the beach to the sea, this is the ‘backwash’. But some of the water sinks down into the sand.

As the water sinks, it forces the air between the sand particles back upwards and this air bubbles out of of the sand, creating the effect we see in this picture, known as ‘pin holes’.

For more patterns and signs on the beach see How to Read Water.

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