What Kind of Sorcery Lets People Swim In This Sand-Filled Hot Tub?

You can try as hard as you want, but you’ll never be as cool an uncle as ex-NASA JPL engineer Mark Rober.

from gizmodo http://www.gizmodo.co.uk/2017/11/what-kind-of-sorcery-lets-people-swim-in-this-sand-filled-hot-tub/