How do you get to the waterfall in mt coronet in Pokemon pearl?

First, you will need Surf, Rock Smash, and Rock Climb (and Waterfall if you want to climb the waterfall). Enter Mt. Coronet from the Hearthome City or Oreburgh City side. Make your way northward through the cave. You will have to go outside in the snow at one point. Keep rock climbing till you find a cave that leads back into the mountain, and the next room should have the waterfall.