This world map has an ocean underneath 14 z levels of ice bordering a glacial cliff, which is the site shown in question. The world map also has a ---lot--- of waterfalls. Just move along the rivers with the height-mapper turned on. The cliff near the underground ocean isn't a big one (just one z level) but it occured naturally, and is haunted and glacial, and bordering an underground ocean, so what more can you ask for? For larger cliffs, check near the various rivers.

Put the information from the following file into your worldgen init file. Yes, I'm aware its several hundred pages long, thats because I made the world by hand. Just shove it into the bottom.

If you don't like the specifics of the world, you -can- regen it and most of the features will be the same, just the biomes will change. In about the same spots you'll get large waterfalls/cliffs/etc, so you can play with that to change where deserts/volcanos/glaciers are.