"William Sommerwerck" > wrote in message
> Nope. The water level drops.
>
> In the boat, the iron ore displaces a volume of water equivalent to its
> weight. Once the ore sinks, it displaces only its own volume of water. As
> water is significantly less dense than iron ore, the water level goes
> down.
>
> You're confusing this puzzle with the one about floating ice cubes. Even
> Mr.
> Wizard got that one wrong

But if the ore is more dense, it would not float in the first place by
itself. That is only a portion of the puzzle. The boat also had air
pockets, lighter material in the hull, etc. If all of it sinks and air
pockets remain, the level goes up.

If you took iron ore by itself, it would sink right away and raise the
level, but it never did float in the first place so it just moved water. .