I have been to 3 different yland cave systems,the longest one and the deepest one was the polar desert one.. there were no ylandium crystals or mutated animals in any of the cave systems and i cannot progress without ylandium dust
I'm on my 3rd island and all 3 cave systems have been really disappointing.
I got around 75 saltpeter from one and 300 gold ore from another. Have a total of 36 ylandium haven't used it for anything yet. First cave I don't remember what I got.
Found a fee camps with some junk items....