As you know, Water Pokemon are mainly found in water. There's a lot of water in Pokemon Ruby, Sapphire, and Emerald. Once you go beyond Lilycove City, you'll enter the open ocean, and you'll find a lot of Water Pokemon there. If you had been more specific, I could have been of more help. Hope I did help, though.
I found it in Cinnabar Isle.. Where you get a sun stone i believe
you have to have beaten the elite 4 and givenh celio on island one the ruby you go to island 4 and find hm 7 waterfall in waterfall cave
the girl at the very end of sunnyshore, she will give you the HM when you get the final gym badge
You get HM Waterfall at the end of Route 18 on the strip of grass in Pokemon Black.
You have to have the HM waterfall, then go straight from green valley..then take a right, go down until you find a big waterfall ..go straight from there. :)
in the cave of origin
HM7 contains the move Waterfall.
HM08 Waterfall is in the Cave of Origin in Sootopolis City.
In Soothopolis, inside the Cave of Origin, where you catch Groudon
You cannot go through waterfalls but you can climb them with the HM waterfall and a Pokemon that can learn it... you will also need the corrosponding gym badge
You go around the ocean until you find a waterfall, then you go up the waterfall with HM07.
in the cave in sootoplis city when your going to fight groundon
Learn waterfall and go to EverGrande city
really rare in meteor falls need surf and waterfall to get to where bagon is
cave of origin. sotopolis city when you need to fight groudon
By itself:only goldeen,seaking With Tm:Mostly any water or dragon pkmn
I found it in Cinnabar Isle.. Where you get a sun stone i believe