You can find Waterfall in the Dark Cave.
get the Hm Waterfall
you find it in the Ice Path
You must get the HM Waterfall which you can find in the cave at Blackthorn city. Teach the HM to any water pokemon then simply use it when you are touching the waterfall and there you go!
It is in the Ice Path. You will see an item ball past a small ice patch. That is the HM for Waterfall.
its inside of the ice path in mahogany town....
in the cave before black thorn city
HM 7 (waterfall) is in island 4
You get the HM waterfall in the same cave you get Kyogre
You get HM Waterfall at the end of Route 18 on the strip of grass in Pokemon Black.
you get the hm waterfall and then teach it to a Pokemon then if you have pearl dimondor platinum you go to mt cornet but for soulsilver and heartgold you go to mt mortor ,mt silver.
you have to obtain the HM waterfall
U find the HM Waterfall in the cave of origin.