Dante's Beach Inferno
When you consider the fact that few people can even build structurally sound sandcastles (myself included), it's easy to see just why sand art is such an impressive medium. It's even more fascinating when you consider that all the time and effort put into the pieces will only last a short period of time anyway.
These particular sand sculptures are actually inspired depictions of the circles of hell, as presented in Dante's Inferno. The sculptures were created in Italy by a team of 18 of the world's greatest sand sculpture artists. The result, as you can see in this Flickr stream by user Htmarcos, is simply breathtaking.