I don't believe you ever sank in the sand, but, if you went into the water and back-floated, you may have noticed that your body is less buoyant. That is, you weren't floating on top of the water; some of you was still in the water!
I definitely sank in the sand - while walking. If you don't walk fast enough, you start to sink. At one point I was running, chasing my hubby and daughter. I shocked myself.
