The right kind of sand

It's also essential that you have the right kind of sand, so that the grains lock together. It's futile to go to a beach with large rounded grains. The Focus team recommends checking your beach by sieving a cupful of sand with a number-50 sieve: you are onto a winner if the sieve retains three tablespoons of sand. When you're building, jiggle the wet sand between your hands so the sand grains mesh together.

Killer Sandcastles

For more information

You can view the BBC Focus magazine's sandcastle building event on YouTube:
http://www.youtube.com/watch?v=v0BzfN3FZzc

Wikipedia on "Sand art and play":
http://en.wikipedia.org/wiki/Sandcastles

BBC Coast on mixing sand and water:
http://www.bbc.co.uk/coast/programmes3/02_bournemouth_plymouth.shtml

All you ever wanted to know about sandcastles at:
http://www.sandcastlecentral.com/

Amazing photos at:
http://www.travelburner.com/2008/01/22/10-of-the-most-amazing-sand-sculptures-from-around-the-world/