anonymity

The concept of a waterfall is the same as a gravity. One uses the forces of gravity and the laws of displacement of a liquid to get air, smokey air, into a chamber. With a gravity bong, one uses one's hand to get the smoke into the chamber, then uses gravity to get it out and into one's mouth. The opposite is true for a waterfall. These are bottles made of almost any material filled with water. The smoker punches or burns a hole in the bottom of a bottle made of most any material. Then, then hold this hole or plug it and fill the bottle. When filled with water, a bowl of marijuana is placed in the hole where you put your mouth. It is sealed there so that smoke cannot rise out past the bowl. Then, the water is allowed to flow out of the bottom hole as the marijuana is lit. When this occurs, a lot of smoke is pulled into the bottle. The bowl is then removed and the smoke inhaled. If done correctly, incredibly large hits can be had and there is very little wasting since all the smoke remains in the bottle.

Cassius

Ummm not exactly accurate bro.

A gravity uses gravity to get the smoke into the chamber just like a waterfall does. With a gravity, you lift the chamber up from the water so that the water level inside is higher than the water level outside. Since it's the same water source and there's an intake at the top (the bowl), gravity is able to pull the water inside down, drawing air in from the top and generating the smoke in the chamber. Of course if the top were airtight, gravity would be pulling the water down but air pressure keeps it up (because if the water were to go down, the air pressure would decrease forming a vacuum, which pulls the water back up).

The only difference between a gravity and a waterfall, is that a waterfall is one-way. When the water leaves the chamber and you're done smoking, you have to put it back in yourself to use it again. When the water in a gravity leaves the chamber and you're done smoking, you merely have to lower the chamber and the water is at the proper level again for you to use it again (by lifting the chamber, creating potential energy, then allowing the potential energy to become kinetic energy in the form of gravity lowering the water level, creating a low pressure situation, which is corrected by the intake through the bowl, once again filling the chamber).