This is pure speculation I heard, but someone brought up a good idea that Degobah (Yoda's home) is actually a destroyed Naboo. Maybe the once beautiful planet becomes so ravaged that it turns into a modern-day Atlantis, covered in thick swamplands and forests. One good point to support this theory is when Luke says: "There's something familiar about this place. It's like something out of a dream." If it were true, wouldn't that be the coolest thing?