Gravity bongs, lungs, and waterfalls are all about the same, except with gravity bongs you can also push the bottle back into the water to force the smoke into your lungs faster and harder.

Also, lungs don't work using gravity. When you pull the bag, it causes a pressure drop inside the bottle, and air rushes in to restore the pressure equilibrium. Same thing for waterfalls and gravity bongs, the volume of the water rushing out causes the air pressure inside them to drop, and air rushes in from the bowl, although you could say it's gravity because it's gravity that causes the water to come out in the first place.

slpntrx5: haha no worries man, in the end these are just technicalities. All this crap I'm posting doesn't matter, all that matters is that these work and get you hiiigh.

Damn, reminds me though, last night tried eating some firecrackers from my first attempt at baking yesterday with a few friends, used some dank NY diesel. Waited an hour, didn't feel a thing, so I took a huuuge hit off a Sobe waterfall with a big bowl of haze, and right when I did the crackers kicked in. Worst bad high of my life, I got soooooo fucked up. Enough to make me stay away from waterfalls for now and stick to my trusty pipe.