I'm pretty much in full belief by this point that this is what Nintendo was talking about when they said the overworld was becoming more like a dungeon. There is a set area (the Eldin Volcano or whatever), and you spend the entire time there making your way up the levels to the top of the volcano. There's (what, four?) different areas in this one place, with each having it's own boss or something of importance. The best I can liken it to is Four Swords Adventures, where you have three different levels for each area, and each has it's own boss or sub-boss. Then, you have the climax at the end, and you complete the area.
It's literally, a dungeon within a dungeon within a dungeon.