I know that Walk On Water only applies to Act 2, but I made a video covering both Acts, just in case you'd like to it as well for your own personal glory. :)
(That should be how it's done, anyway)
This is also(unless you die without restarting) a guaranteed way to get S Rank, to help you with Big Bang/Blue Comet/Blazing Meteor/Shooting Star/Bright Star, if you need it. This covers an alternate(and in my opinion, easier) way to get out of the rising pink water pit from the video above. You don't NEED the skills I've displayed in the video--they're just to show you what I'm using. Enjoy!
POST EDIT:For a more detailed version on what to do in Act 2, I've added a video with commentary that should explain everything.