When I take Andy to the lake or beach, it is hard to keep him from reaching down and grabbing the sand and putting it in his mouth. He doesn't understand "no", and loves to put everything to his mouth except food. He only has to get a small amount of sand in his mouth before he will get an upset stomach from it. I like to sit Andy at the shore in a few inches of water and let him play with a water-filled bucket of toys. There is still a problem of him reaching down for the sand under the water and he wants to put it right in his mouth. So in the past, I have found that if I sit Andy in an inflatable raft with a floor on it and put water inside, he can sit in there and play in the water without access to the sand/rocks/shells.
We have since found a better solution, which is a River raft. My inlaws picked them up for floating down the river, but they are perfect for Andy. It is an inner tube with a mesh bottom on it. This way he can float in a few inches of water, and it doesn't have to be filled up. He doesn't have access to the sand and the rope around the tube can be tied to my chair to keep him from floating away. They also have cup holders, which we used for his water. It is a better alternative to him sitting in a chair in the water, because it keeps all his toys contained. He hasn't learned to throw them out of the raft yet. The one we bought is the Intex River Run inner tube. This raft can be found on Amazon, Walmart or Walgreens. We love it and so does Andy!