Last year we vacationed in Maine, and there was a guy there who was going for the world record of the tallest, free-standing, hand made sand castle in the world. I was talking to him and he was explaining to me that he uses a specific kind of sand that packs better than typical beach sand. The grains are smaller and allow for the grains to really pack together. I asked him, what happens if it rains, and he said that is not really affected ,and actually helps in the packing process. He eventually did break the world record. CBS news team was there covering it. The detail was also crazy. It was neat to watch the progress he made each day. He also let the kids help out with the moat around the castle.
It stood about 30 feet.
Here is a pic of the the top of the castle. The day before the guiness worl record judge came, a sea gull landed on top of the castle. He was very nervous. No damage. ( look at the pic closely and u can see the bird). And also a pic of my kids helping. Proceeds went to charity ( they sold shirts and other things related)
World Record Sand Sculpture