I've always wondered this, too. Good luck!

Water is lighter than sand, the pressure makes it move since the sand cannot. Like Chris said, it is like a sponge that you apply pressure on with your hands (at first, I didn't understand his comparison).

So, you went to the beach huh! :) Best from your bestest Düsseldorf friend!

Thanks Chris and Mareen!

@Mareen -- Hello to my best Düsseldorf friend! (Yep! Here in Brazil for another 7 days.)

magic.

Nobody resists coming to Brazil and not buying a pair of Havaianas.

Have fun in your stay!

Wet sand has a different refractive index then dry sand, so your body weight pushes away the water and...

I think the same thing every time I go to the beach

my guess: watch how the ring gets bigger as more weight is applied. the weight of your foot displaces the sand. the sand under your foot goes down and out. the sand around your foot raises and the water stays level.

this clip is interesting too: vimeo.com/clip:176132