Photo of Bluebell Woods in Sussex Photo of Bluebell Woods in Sussex

The Tombolo


A tombolo is a thin strip of sand or shingle that is formed by wave action around an island. The new thin strip of land then keeps that island connected with the mainland.

This beautiful sandy tombolo may be of especial interest to readers of How to Read Water because its formation is a great demonstration of the way waves bend.

As the tablet below explains,

“The tombolo was formed by waves from the Atlantic to the west being bent (refracted and diffracted) round the island on either side and meeting on the eastern side of the island.

In the meeting zone sand and pebbles on the sea floor were swept along by the waves and accumulated to form the tombolo.”

There are very clear parallels between this action in these Shetland waves and those used by Pacific navigators half a world away.


(If you feel like a fun test of your observational skills, use this blog to try to answer this question:

What colour is the dog’s collar?

There are two points available.

(Answer at the bottom of the page.)




Answer to the observational test:

The dog’s collar is red with white spots.

(try looking at the bottom left corner of the second image.)


My thanks to James Axtell for sending in this excellent pic of the largest active tombolo in the UK, at St. Ninian’s Isle, Shetland.