Coins are supposed to sink. When you toss ‘em in a fountain, they drop right down to the bottom, right? Not always. There’s a trick that can actually make metal coins float, and it’s totally trippy to see. You carefully level the coin (which needs to be made of aluminum and not zinc) onto the surface of the water with a paper clip, and then slide the paper clip away. Boom! You’ve just become a sorcerer. The metal coin is floating.
Source: Gizmodo – How to Make Metal Coins Magically Float on Water