Water storage during hurricanes or snow storms, after scrubbing. . I scrub the tubs and fill them when tornadoes are expected too. I also clean the washing machine and fill it up. There is not much worse than being without water.
When the girls were little I would put them in the dry tub to finger paint. They could paint the inside of the tub and the walls.
I also use the tub to wash non-live items such as lampshades, laundry baskets, etc.
And my contractor didn't understand why I didn't want walk-in showers............
I used it for that all the time when I had metal blinds. Now I have the wood (not real wood....they are the white ones) and don't put them in water. I just vacuum them. The cords don't get dirty. I don't let anyone smoke in here.
I still have the metal ones in my bedroom, and plastic ones in the rest of the place. I need to replace them and I will when I paint the apartment again.
A long time ago I was going to enter a bathtub into the bathtub races between Horseshoe Bay (near Vancouver) on the mainland and Nanaimo (Vancouver Island) but the officials put a stop to the exercise because the Strait of Georgia was getting too cluttered up with drunken sailors and sunken bathtubs.