It’s possible to turn a bunch of sand into a fluidized liquid using pipes and just the right amount of air. A dude called Mark Rober on YouTube is showing people how to build their own fluidized air bed. This is the technical name for a system that can turn solid sand into something akin to a fluid.
Rober uses a bunch of PVC pipes in a small container that would normally be used for storing items in the closet or garage. The catch is making the holes just right. According to Rober, this tech is used commercially today to ensure that grain flows correctly in a silo among other things.
The catch was that there were no instructions for doing this online. Rober combed through patent drawings for industrial size fluidized air beds for ideas in making his small version. He says the key was to use a bunch of small air inlets rather than a large one.
Rober decided to scale the system up and turned his hot tub into a fluidized air bed as well so you can swim in sand. It reminds me a lot of quicksand, which I thought would be much more of an issue growing up than it really is.
You will need to be sure that you build this thing with attention to details, the holes must be drilled at precise angles and distances apart. The result is the ability to swim in sand. Very cool, but it sounds like you would be getting sand out of places sand shouldn’t be for weeks afterward.