Board Thread:Lore Discussion/@comment-108.253.68.177-20131021030335/@comment-86.143.82.209-20150110043226

"But this questline is different. If you want to explore the Shivering Isles rather than do the main quest, you cannot ignore the main quest completely"

Yes you can ignore the main quest completely, with the vanilla start you can do what the heck you want after you escape form prison.