Submerged brush...

That's Bass fishing.  Aren't we talking about Walleye?  Fishing thick cover for Walleye is often over looked by many anglers.  Fishing cover is tough and it can be a huge pain.  Cover holds monster Walleyes and they will bite all day from their hiding spot.  Cover is perfect to ambush bait fish and small game fish.  It provides cover and concealment and there is usually less fishing pressure.  If you're not Bass fishing for Walleye, you are missing out.