Need help with making textured walls

[Kaylum Dicks]

I'm really wanting to do a revamp of my bathroom, I'd love to make it look like an undersea cave. My nerd-fu seems to be weak and I've looked around, but I can't seem to find the right search. Is there a way to redo the walls with some sort of texturing material to make it look like the inside of a cave? I'm pretty good with my hands, I'm great at following directions, and pretty good at basic sculpting, so I'd like to think something like this is doable. Any help on what to search for, or links to a good tutorial would be awesome.